Depending on how small the chickens are, and how big and sturdy the feeder is, you can sometimes use a chick feeder. Just use common sense in this case. If they can't reach the food easily, get a smaller one, though this will probably not be a problem with a chick feeder. If they tip it, move it around a lot, and it's definitely shorter than their backs, get a larger feeder.
Even if it's technically the right size, it still depends on how much you're willing to dote on them. If it needs to be filled two or three times daily, and you're okay with that, fine. If it does and you're not, opt for a larger feeder.
You can use the exact same criteria when deciding when it needs to be upgraded as they and their diets grow.
Hope this was helpful.