I don't know what's in yohimflame, but the minimum amount of yohimbine taken orally is 0.2 mg / kg per day.
So a 90 kg person needs 18 mg of Yohimbine per day to achieve the desired lipolytic effect.
To assess your tolerance it is advisable to start with about 1/3 of the optimal dose (so a 90 kg person would start with 6 mg) increasing the dose over a period of a few days (usually 2-3 days).
It must be taken on an empty stomach - This is crucial because even a small insulin response will prevent any effect of the yohimbine.
Taking yohimbine with food will produce a greater insulin response than taking food alone (this is linked to the α receptors in the pancreas).