Question about hatching duck eggs

I was thinking about starting to raise ducks in the spring. I'm not looking to get many, so I thought I might order a dozen eggs and hatch them in my incubator. If I end up with 6 or more... great. I've been reading up a bit and it seems they need a much higher humidity. It looks like 85-95 % RH
Does anyone have any tips for increasing the humidity in an air circulating incubator? I hatched chicken eggs in it last year and the RH was 65% with the vent closed. I think I saw some people using spray bottles to mist the eggs.

Does anyone have any other ideas as to how to go about doing this?

Thanks

A wet sponge in the incubator and misting help.
This is anecdotal but my freind also put some of his mom's oxygen into the incubator just before and during hatching (eggs from the same ducks).
He had a 90+% success and i had a 20% success rate.
Mabey more humidity and O2 for the epic work of hatching?
Good Luck

My GQF Sportsman has trys that you fill with water and slots for large sponges to sit in vertically. These are located in front of the main fan and keep the humidity appropriately high. I have not hatched duck eggs yet, but with my chickens, quail, and turkeys I average 80% hatch rate.