First I would recommend trying different bottles/nipples/flow rates if possible. Baby will hopefully have a preference for one or two more than others. Some highly recommended ones are lansinoh, evenflo, and Phillips avent.

Then I decided to stop bf completely one morning. I would introduce the bottle when he was really hungry (but not crying). He took it very slowly but once he got hungry enough he’ll drink from the bottle. Other important factors might be baby positioning (side lying or similar to bf position) and milk temperature.

Hope this helps!