Electric fencing has been around a long time, and has been used with chickens since at least 1960. The methods used then still work today.
The earliest mention I’ve seen of electric fencing with chickens was in a 1960 issue of “Egg Producer” magazine. The electric fence consisted of a single strand of wire 4-5″ off the ground. That’s it! This single low wire was enough to hold in the hens and discourage predators. Sometimes they added a second wire at 8-10″ off the ground, but it was mostly just for show.