Need advice on adding hot wire to existing fence

I have an inner chicken coop and run that are high security, but the birds complained so I made a gate into a much larger area. Less secure, it’s a 6 foot poly deer fence around 270 feet in perimeter. Figured it would keep out the daytime predators like dogs and coyotes, but after 4 months I lost 2 birds at once (only feathers left.) I trapped a raccoon the next night and when released, he darted out of a small hole in the fence base.  Not sure if he’s the culprit but I’m wondering about adding a hot wire around the base of the fence for added protection.
I do not know much about electric fence. Assuming I should run a wire around the outside of the fence, a few inches off the ground. The fence is on T posts and I know they make clip-on insulators. Not sure about poly line, tape, or standard metal wire, nor how strong of voltage for predator deterrent. Any thoughts are welcome, birds are on lock-down in their small run in the meantime!

Trapping the Raccoon and seeing it exit "sounds" like the culprit has been identified, or has it? Honestly, this sounds much more like an aerial attack.

I do not want you to go to the trouble and expense of adding a hot wire, assuming this will solve the problem, without considering the likelihood of some sort of bird of prey, being the true culprit, at this time.

Now obviously, there is insufficient ground up protection so yes, adding an electrified fence should be done regardless.  All that sort of mesh fencing is doing is containing the girls, predators will either go "through" it, over or under it.  Consider electric netting, set up a few feet back from existing mesh, or to replace existing mesh entirely. Not sure of the conductivity of cheap chicken wire, but that may be a cheaper alternative.

Assuming the coon IS the predator, if running hot wire, you would want to place wires every 2-4 inches; their head can fit in/through any gap the size of your fist.

BUT, my gut is you are dealing with aerial predation (or soon will be). Old patio umbrellas, netting, fishing line every 3-4 inches overhead should be seriously considered. Perhaps a LGD, or guard geese, or Pea Hens added to the flock...

The birds of prey are currently teaching their young to hunt. Those who are lacking proficiency often end up seeking the easy prey; and once discovered will keep coming.