I am getting a raised mole removed with a radio frequency device. How likely is it to grow back or for the pigment to reappear?

In general a pigmented mole should be removed completely to prevent recurrence and achieve the best cosmetic outcome.  Also it might need to be evaluated to make sure it is not a potential cancer.  Ablation will prevent evaluation since it will be destroyed.  There are  a number of techniques to be considered.  A board certified plastic surgeon can educate you on all your options and choose the best technique  to achieve your goal. 

A mole should never be burned via a laser or RF device. This is incorrect and potentially dangerous. Moles should be sent for analysis. Depending on the kind of mole- Shave or excision are the better techniques. I would see a dermatologist as only dermatologists have training to evaluate moles and interpret its pathology.