Try Pill Pockets (vet or pet store) or a moist treat to see if you can hide the pill in that; some have success with cheese. If it doesn't have a strong odor and is ok to crush (did vet say?), mix in with wet food. If he won't eat at all & you have to "pill" him, try to hold his mouth open with one hand (push near his back teeth), then drop the pill in with the other and immediately stroke his throat several times until he swallows at least once. If possible then get him to eat or drink something to make sure it goes down.
Good luck! How old is he?
Good luck! How old is he?