  We report on the compensation of excess micromotion due to parasitic
rf-electric fields in a Paul trap. The parasitic rf-electric fields stem from
the Paul trap drive but cause excess micromotion, e.g. due to imperfections in
the setup of the Paul trap. We compensate these fields by applying rf-voltages
of the same frequency but adequate phases and amplitudes to Paul trap
electrodes. The magnitude of micromotion is probed by studying elastic
collision rates of the trapped ion with a gas of ultracold neutral atoms.
Furthermore, we demonstrate that also reactive collisions can be used to
quantify micromotion. We achieve compensation efficiencies of about
1$\:\text{Vm}^{-1}$, which is comparable to other conventional methods.
