Rauwolscine is what is known as a diastereoisomers of Yohimbine. There are 3 diastereoisomers, the other two being corynanthine and 3-epi-alpha-yohimbine. Basically, it is an alternate form of it with slightly altered properties.
It's mechanisms of action are very similar to yohimbine, as it can act as an Alpha(2)Adrenergic antagonist and thus aid in fat burning (not so much by inducing fat loss, but by alleviating pressures the body exerts to preserve fat mass; its like preventing the body from stopping the fat loss, but doesn't induce it directly). Rauwolscine shows some promise in being more effective due to higher potency on the same receptor.
It also shares the same aphrodisiac and mood-elevating effects as yohimbine, although the potency on this relative to yohimbine is not known.