the artificial harmonic isn't actually a tap - you fret a note as normal, then touch the string over a fret higher up, then pick the note with a plectrum or finger. It's the same a a natural harmonic, but with the root note moved.

You might be talking about fret tapping, which is where you, for example, play an a on the fifth fret of the E string, and then tap on the 17th Fret...