I want to say that Ti would be high up on the list, but what I'm thinking of is probably really Ti getting broadcasted by Fe ("Society is deluded, I'm one of the few rational people, etc. etc."). I know, for my part, I'm a very narcissistic person, so it would probably be one of my own main functions. I have a tendency to convince myself that I'm very good-looking, until I glance in the mirror or think about a time when I've glanced in the mirror. That would be weak Se and Si, I'd say, and probably . . . strong Fe, since what I'm focused on, when I have this narcissistic delusion, is a sense of how my looks are (not really) being received by others.
Really, I can't imagine Fe not being involved in narcissism. Narcissism always entails viewing yourself from an outside, basically social perspective, and often takes on a very demonstrative aspect. It is unclear to me what means Fi would have of bending back on itself in such a way that narcissism would become possible for it; Fi tends to internalize the self rather than externalize it, and that leaves narcissism with no means of propping itself up. Since narcissism is basically personal in nature, I don't believe any of the other functions could be involved in it, except in a very non-fundamental way.