I do not free feed, once my birds are out of the brooder box and the grow out pen.
My flock (see below in sig) free ranges on the property, all day long. I feed them once, in the evening, to ensure they go to bed with full crops - and are then eager to free range in the AM.
How much to feed them took a bit to dial in. I started at 1/4# dry weight per bird, then slowly lowered it until I found a good balance between them demanding more/gobbling it all in one-two minutes and them walking away with uneaten food left in piles. Then keep watching, because it does vary seasonally - not a lot for me due to my climate - but I understand its more pronounced for those further north.