Usually you need to use rectangular patches with rounded coreners. It's best to actually locate the patches by seeing where you "rub". It varies depending on vang, out haul and (if you rig a) preventer.
I'd put a temp "sticker" where you think it the patch(es) should be, then move it around until you are sure. Then actually apply the patch in the right place. The patch, if re,over leaves a residue that can attract dirt.