The "howtos" out there don't really show you how hard to pat the baby when burping it. They seem to focus on positions and such, but they stop short of actually doing it.
I want to know that I'm patting/rubbing him hard enough to be useful, and not so hard that I would make him uncomfortable (or worse, I suppose). Use comparisons like "as hard as you would knock on a bedroom door while trying not to wake someone if they are sleeping", or simply link to a video where someone is actually burping a baby (especially one that does not burp easily!)
My baby is 1 month old.
edit: I just want to add that there are several good answers here. Thanks!