>Can you provide a source to where he references himself as a psychologist?

I can and I will, but why is a source needed?

This is a pretty well studied aspect of Nietzsche (lots of books, papers, critique of later philosophers on the matter etc), and it's evidently true even in parts of his works where he doesn't openly talk about psychology (ie. you don't need to openly name a thing to practice it).

If people have read Nietzsche, they would have witnessed his affinity for psychological examination of philosophy, morality etc. If they haven't, I don't see why would they need a pointer to such a source. What use would that be if they have not read the rest of Nietzsche?

I'm saying this because to me the request sounds like either "I know Nietzsche and don't believe you, where's the proof?", or "I couldn't be bothered to read Nietzsche, but don't believe you anyway, where's the proof", both of which I find problematic (the first because I don't believe someone can read Nietzsche and miss this aspect, and the second because it's a little lazy and insulting).

For me such a request would make sense if it was for a controversial and not well known aspect of someone's philosophy. E.g. "Where does Marx say socialism is possible in a non-industrialized country". But not something well known, like "Where does Marx say he is in favor of workers over capitalists?". If someone doesn't know the latter already, then a reference seems moot. They can just read a 101 on the subject.

In any case, here are some references from "Beyond Good and Evil" and "Ecce Homo":

"Never yet did a PROFOUNDER world of insight reveal itself to daring travelers and adventurers, and the psychologist who thus "makes a sacrifice"—it is not the sacrifizio dell' intelletto, on the contrary!—will at least be entitled to demand in return that psychology shall once more be recognized as the queen of the sciences, for whose service and equipment the other sciences exist. For psychology is once more the path to the fundamental problems".

"In that the NEW psychologist is about to put an end to the superstitions which have hitherto flourished with almost tropical luxuriance around the idea of the soul, he is really, as it were, thrusting himself into a new desert and a new distrust"

"Wherever sympathy (fellow-suffering) is preached nowadays—and, if I gather rightly, no other religion is any longer preached—let the psychologist have his ears open through all the vanity, through all the noise which is natural to these preachers (as to all preachers), he will hear a hoarse, groaning, genuine note of SELF-CONTEMPT."

And in case in these it's not clear that he speaks of what he does and himself, because he frequently does so in the third person, even though the overal book and context makes it evident, here are some more:

"What man, before my time, had descended into the underground caverns from out of which the poisonous fumes of this ideal—of this slandering of the world—burst forth? What man had even dared to suppose that they were underground caverns? Was a single one of the philosophers who preceded me a psychologist at all, and not the very reverse of a psychologist—that is to say, a "superior swindler," an "Idealist"? Before my time there was no psychology. To be the first in this new realm may amount to a curse; at all events, it is a fatality: for one is also the first to despise".

Or how about a boast of being the biggest psychologist:

"The fact that the voice which speaks in my works is that of a psychologist who has not his peer, is perhaps the first conclusion at which a good reader will arrive".