C.M.
My son had a hard time taking a bottle at first. We got the playtex bottles with liners. (more expensive, I know) What I did was every time I would try to give him a bottle, I would push on the liner to squirt some milk into his mouth. That way he got a taste for what was in the bottle. It still took some work, but just watch for his signs, and don't get frustrated. If he senses you getting upset, it'll be even harder for him.