Danny, I'd say you want to pick the category based on whether the pay site being promoted via the free site is more focused on the fetish of being trampled by a foot or more focused on the power exchange dynamic of being trampled by a dominant female.
Of course that's fine with sites which have categories that finely tuned. Otherwise you'll be stuck with picking between two categories (if you're lucky) like Fetish and BDSM (or worse, just Bondage). In those cases I'd go for whichever category has more FemDomme content listed, since you're fishing for the most possible interested surfers.
And you probably already know to use the title and description to call out other sub-niche surfers with words like toes, legs, high-heels, boots, knee-highs, thigh-highs, marks, pain, breathing, suffering, etc.
Note: I didn't see Bluebrit's post until I was done posting mine, so I wasn't singling him out and picking on his reply about two categories. I was actually picking on everyone who still uses just BDSM and Fetish to throw all "that stuff" into. |tomato|