I don't do the PF9,..but I do quite often carry the P-11 or the P3AT, both sans holster with the belt clips. The clips do not interfere with carrying while holstered in my choice of holsters either. The P3AT in a DeSantis pocket holster,..the clip easily slides on the outside of the holster. I generally carry the P-11 in a Yaqui minimalist styled holster, OWB at 3-4 o'clock. The pistol clip actually helps anchor it in position. Hope that helps.
Some folks will chime in here soon and tell you it's unsafe. I haven't had issue,...I have carried both guns this way for years,..and I am what one might say quite active .... never had any issue in the guns moving when carried IWB with clips while wearing a good belt. The belt snugs them in nicely and holds them in position well. I have carried briefly without a belt. I do not recommend that as a steady mode of carry.
YMMV