Free feed just enough feed so that at the end of the day it's mostly cleaned up. You will draw less rats this way, and chickens prefer fresh feed. If you can't then free choice is fine - just clean it out weekly to prevent the troughs from filling up with the waste parts.
This will keep the birds from overeating when feed is first put out.
If feed wastes, try using the waste-free V shaped feeders that you can easily make yourself using some wood and lathing strips. The feed falls back into the feeder and can't be knocked out (like large round hanging feeders).
If you need to give something like a probiotic or supplement, your hens will be slightly hungry in the morning but not ravenously so. You can feed them a wet mash with their treatment in it, and then feed them the dry mash for the rest of the day.
Grains (like oats, not scratch which is a treat only) can be fed in a separate bin if you supplement with them.