Do you have a pet crate the chick can be comfortable in? You could place the chick in such a crate in the run until it gets a little larger and develops self confidence. By self confidence I mean that the chick will not be so afraid of the adults that it gives up trying to evade them and instead offers itself up to abuse without trying to protect itself. Often a safe enclosure while the chick and the adult flock are getting used to one another will be enough to achieve successful integration.