It's usually slow going when you first introduce a bottle to an excl breastfeeder. Things that some moms find helps are:
-Having someone other than mom offering the bottle (ie mom leave the room! babies can smell mama milk!)
-Offering the bottle before baby is very hungry (so trying b/w nursings when he may be more patient)
-Hold baby in the nursing position when bottle feeding (teach dad how to feel like he's bfing)
-Dripping a small amt of pumped milk onto the babies lips and letting him lick it as you gently offer the bottle
-If he doesn't take it, just breathe, nurse, and try again in a day or two. (It sometimes takes several tries)
Good luck! With my 2nd I had the option of going to him at lunchtime and nursing which helped both of us greatly! Welcome to the forums!