ETA: if chicks, put in a small dish, where they can pick up pieces of it. if adult birds, toss on the ground or offer it in a free-choice dish where they'll eat some when they need it.
We offer two sources - one near the nesting boxes so the ladies can grab a beak-full when they go to lay and another one near the free feeder down below.
I took an empty tuna can and nailed it to a deck post, high enough that the mower can go under it, which puts it at just about the right height for them to stick their beaks into it. Then I just keep it full and they help themselves when they need it.