The known rate-limiting factor in forskolin's bioavailbility is its solubility. Forskolin is basically insoluble in water, so dry forskolin has
extremely poor oral bioavailability. In this respect, it may be worse than any other ingredient in common use. That is to say, bioavailability well under 1% is a safe bet.
And there's an unknown factor, a wild-card: Nobody knows how forskolin is metabolized
in vivo. The small fraction that's absorbed could be subject to an almost complete first-pass effect.
For these reasons, I wouldn't recommend forskolin.