Unlike lasers, which work by heating melanin or other chromophores (light absorbing chemicals or structures inside the skin), radiofrequency works with electricity and ultrasound works mechanically, with sound.. The electrical properties of the skin are exactly the same in light skinned or dark skinned people, so skin colour plays no role in radiofrequency treatment (RF is basically high frequency electrical currents). In much the same way, the mechanical (acoustic) properties of the skin are exactly the same in light skinned…