Free range my ducks?

I have one Drake + 5 hen khaki Campbell's in with two hens and one rooster I want to start opening their pain up to let them free range a little bit now that the grass is getting really green but I'm worried because the Ducks are a bit more skittish and don't like being around me when I walk in I'm wondering if no fly away when I start opening the pen up and letting them out

From my experience with a half dozen Peking ducks is once they find your pond (if you have one) and they're skittish, good luck getting them out again.
My friend had a few Campbell's and upon being released one flew away and came back a few days later. Those ducks avoided the pond until they figured out what it was.
If I were in your shoes I would try to get them rather tame and make sure that there is plenty of familiar food outside so they'll stick around. I would make sure that they will eat grass before letting them out because they might not know what it is.
Good luck and happy ducks!

My ducks don't like anyone near them, and will take a little flight if I approach quickly. Most domesticated ducks fly as well as chickens, which is just a glide and fall, with style. Mine climb on top of their pen to look out for predators for the rest of the flock, only a few prefer the 'scout' role. They happily free range in the backyard pasture (permanent fence). They are easily herded, and will typically go where you want if you extend your arms out and look really wide. Use your arms while extended and close toward your body like youre clapping and they move forward from me.  

My ducks come running when they see their food being filled up, or my red cup even when empty. Though they usually see it full of whole corn to snack on. If I stay still, the ducks don't mind getting really close, regardless of food. They will eventually get used to you.

The first farm I cared for had 40 ducks, where they were kept in an open pen with a few places that had a roof. The ground predators were kept away by guard dogs on the farm, and there were occasional flying predators at night, owls in particular. They had so many ducks and too many eggs to eat so the losses were recouped when laying for ducklings. Anyway, the ducks were completely free range and had no issues going back home. They would go down to the creek several hundred feet away on nice days, and other days they would follow up the hill to eat grass and bugs. They were a happy flock, and generally stick in groups of 1 or 3. So they liked to stick together. The ducks weren't particular to allowing anyone close to them, so the flock would move away when a human approached.

Another farm that I helped build started with ducks and put their pen right next to a pond. They also started with about 30-40 and bred to about 60 before starting to cull. To get them out of the pond and back in the pen, they would fill the feeders at night only in the pen before locking up their pen and every duck would start running into it. Their muscovy duck breed wouldn't be easily as fooled, and would stay in the pond, sometimes overnight with the chance of predators. They lost a few muscovy duck that way.

Your flock should know where home is, if they've been in there for a few weeks, they especially know where the feed is. If you fill it up at night they will know what's going on and go back in to eat the easy scratch. Chickens will naturally go back in their pen before dark with or without feed. My ducks will do the same. Although the first flock liked to lay down right at the opening of the pen, my second flock go right in before nightfall like chickens.

If you have a pond, you might want to consider making a duck house that floats in the water with a duck-only water entrance. No predator will be able to dive under water to enter but a duck.

I agree that training is important - if you can train the leaders, the rest will follow!

Muscovy - they only get fed at bedtime, and they greet me at the Noisy duck pen and follow me up the field. If the routine needs to change, carrying a feed bucket or their feed scoop is usually enough.

Khakis (Noisy Ducks) are flightier and more at risk from our day-time flying predators, so they are usually penned unless being fostered by a Muscovy Mom. They also do more damage to the field if it's wet than the Muscovy do. They do think that Lemna (Duckweed) is "quack coca__e", so I've used that to bribe them closer, but it's still hard to get them to take it from my hand, no matter how much they look at me thinking, "I really want that duckweed, but there's a big, scary human holding it - why doesn't she just toss it to me!!!" If I really needed a group to follow me, or respond to a location marker (I've heard of ducks being trained to a flag on a spike so that the farmers can move them to a location, plant the flag, and expect them to be in the area read for bed in the evening) I'd try associating the marker with a feed they really like, and restricting access to that feed except as a reward for following the marker. My goal for this year is to try to give them several paddocks so I can rotate them, and to get more small ponds for growing Lemna.  

We have 3 geese in the field to try to deter daytime predators, but it's not at all fool-proof. The Eagles get hungry in Feb and target our female Muscovy as the smallest birds free-ranged.

I've always had 0 issue free ranging, even the pigs. This is helped by the amount of land I have and the complete lack of vegitation  anywhere off my land. The ducks would wander about but everyone always went back to the barn at night. Pigs, peacocks, ducks, chickens, turkeys. Everyone. On their own, 0 issues.

I used to always let my chickens out and they would just go back and Roost at night but I just shut the door in the evenings but now that I have these ducks that are a lot more skittish I'm just worried that if I do let them out they might take off and fly to the pond on the neighboring property or not follow the chickens back into the coop

If you have some stakes and mesh fencing, set it up right outside the coop and let them out there for a few days. At least waist high as long as nothing is up against it. This might get them outside the coop and prevent them going too far. If the pond is far enough and cannot be seen in a straight line, the ducks may not notice. I have a running creek right in the back of my fence, the ducks could potentially squeeze through the semi-large holes of the fence but stay inside my backyard pasture. When the flock had ducklings - that was a different story - the ducklings went through without issue and the duck hens squeezed through to be with their young. Then they followed up the creek to a point where I thought I lost the whole flock once I noticed they were gone. They all came honking and barreling back after a predator likely attacked and took a few ducklings, since some were missing. They remembered where safety was. A pond nearby does seem to pose a possibility that they would head over there free ranging. If they feel more comfortable there than their home, it might be a challenge to herd back, especially if its a big pond and no boat! They may not pay much attention to the chickens roaming around and going in at night, however, since they've been kept together they may have some feeling of affiliation.