So, get something like this: Moultrie Hanging Feeder.
Then hang it from a strong limb or some apparatus like this:
Three seconds once or twice a day for 16 hens reels the girls back home. They clean it all up in about 30 minutes and then go back to ranging. Again, I just do this as an aid...
I use scratch in a hanging game feeder. Our flock ranges during the day, and I use the scratch to keep them straying too far or at least get them to come back to home base a couple of times to keep them close.
Currently, the coop is opened at 10am; the feeder goes off at noon for two seconds...