[Ulzgoroth]

Based on the ability (which has 'based on IQ' as a modifier) and the total absence of the Innate Attack skill in GURPS Psis, I don't think Innate Attack is relevant.

It might, however, be the second case with the TK Bullet skill used in the second roll instead of Innate Attack. Considering the costs of failing a manifestation, and the strangeness of being more likely to suffer them if tossing pebbles at small or distant targets, I'd be strongly inclined to this interpretation.