How do you prevent chicken from sticking when searing?
Use a heavy bottomed pan. Heat pan medium high.  Add oil.  Place chicken skin side down.  Don't move the chicken.  Once you see browning, gently see if the chicken releases.  If it does not, leave it.  It should release with some gentle nudging, but it should not be moved if it doesn't release.  Usually the issue arises when the meat is flipped or removed too soon.