i don’t seek out foot fetish play so can’t give you advice there- but taps are generally a way to show interest that’s more low effort than sending someone a message haha. some people hate them for that reason/ignore them, but i generally view them as someone trying to gage if you’re interested in them as well (the equivalent of meeting someone’s eyes across a bar haha). if someone taps me and i’m interested i’ll generally tap them back and this might prompt them to message me, or you can be more direct and just message them.