You can buy penicillin, which is what I usually use. It's ten-fifteen bucks for one of the smaller bottles, and a bottle lasts a year or longer in the refrigerator. You'll also need syringes if you go that route.
Dosage for standard chickens is .25 cc once a day for four successive days. Injecting under the skin (SQ) is slower release. Injecting into the muscle is faster release, but more painful for the animal.
We usually buy medium-sized needles so that we can re-use them, but we're cheapskates.
You can also give aspirin for pain--in chickens, the dose is one quarter of a standard (325 mg) aspirin. I'd crush it into water and divide the water. She should drink it.
Keep her in a warm, dark place. It helps their recovery. I'd also trim the feathers around the wound a bit for easy access, and make sure it's completely clean with a saline rinse--1 tsp salt to a pint of water, I think.
Personally, I use Blu-kote for everything, but there's a sticky disinfectant product called red-kote that's far less painful. It's a disinfectant coating, and you may want to invest in some. But iodine may work well enough on its own.
Good luck!