Rotokite theorized it with two kites that would be controled like for all yoyo systems.
The same with only one kite, unless a mechanical means is found in order to lift the kite in every rotation then depower it by stopping the rotation.
The same for all AWES, the cubed cosine loss increasing as the elevation angle increases, about are the considerations of flight path with large radius (Makani) or small radius (here) or rotating with joined wings (Rotokite) or figure-eight.
For all yoyo systems I think a simple way to calculate the power is the force x 1/3 wind speed reel-out x 4/9.
As Goldstein indicates half of power for a rotating kite in regard to crosswind flight, can deduce half of force. So all other things being equal a Rotokite with two joined wings would have 6 kg (60 N) force, so 30 N for a single wing, perhaps less.Taking also account of Betz limit 4/27 for yoyo systems.