TL;DR 144watts
The transformer (power supply) I'm seeing on their site is rated at 24v/6a max. If you pull the full 6 amps AND I'm doing my math right, that would mean, at the max, it could draw 1.2amps (at 120v, which should be the case since you're in the states) out of the wall.
(120v x 1.2 amps) OR (24V x 6 amps) = 144watts
I'm not familiar with Reef Brite lights beyond being aware of their existence and seeing them in LFSs on display. So I don't know how many lights the power supply can drive, but if that 24v/6a power supply is the one that comes with your kit, 144w will be the max it can draw, based on the rating anyway.
Though if someone can verify that with an amp meter or kilawatt, we'll know for sure.