// Use nFeat on oTarget. // - nFeat: FEAT_* // - oTarget void ActionUseFeat(int nFeat, object oTarget);
NWN Lexicon states, and I quote, "This action cannot be assigned to PCs." This does not mean the PC as the caller of the function cannot use the function, only that another object cannot assign it's use to you. Even then, you still need to have the feat to get any use out of this function. It's also a good idea to be wary of what the feat does and who oTarget is.
For example, Smite Evil targeting yourself does not mean you are calling Smite Evil, it means you're attempting to use it on yourself and you'll get a pretty error message when you do. An appropriate oTarget in this case would be defined as GetSpellTargetObject or GetNearestCreature. However, if we were running a feat with a healing effect a PC would be a perfectly valid oTarget.