A combination of rubbing and patting helps, cuz sometimes it feels like ur patting too hard to get the burp out. I found that also works.
Start patting toward the bottom of his back and work your way up.
I always did one of two things. Pit them up to my shoulder and patted their back or sit them in my lap, slightly bent over. Cradle their head with one hand and pat their back with the other. Hope that this helps!