Does it matter if you need a license, long about now?
I don't advocate illegal activities, but this is one of those times when swift action will save the day. You either let the fox rape your chicken yard out of fear of retribution, or stop him.
Have you ever heard of a shotgun trap? Basically it is the end of a shotgun barrel, baited. You make a funnel of plywood or something else, so the fox has to enter straight on to the barrel's end. When it pulls on the bait - a string attached to the bait pulls the trigger.
It is Rube Goldberg-ish, but is reputed to be effective. Use bird shot and have a safety backstop behind the target area to contain the shot if there is a miss.
It's loud and it is crude, but then so is Hulk Hogan. And he's pretty effective. If you own a scatter gun, this is a pretty safe alternative in suburbia.