Photonic radio frequency (RF) switches are promising to replace conventional electronic RF switches in modern RF communication systems owing to their high switching speed and immunity to electromagnetic interference. However, existing photonic RF switches are generally based on frequency or polarization filtering. Thus, they require more light sources and filters to increase the number of switching channels, consequently limiting scalability. We propose a silicon-integrated photonic RF switch based on optical switching. RF signals are first modulated into the optical domain and switched through phase control of the phase shifters in the optical switch. Switching is not related to the frequency or polarization of the optical carriers, thus reducing the number of light sources required. Experimental results demonstrate 10-GHz switching of two RF signals with frequencies of 20 GHz and 30 GHz. The proposed photonic RF switch can be further expanded to form a large switch matrix, possibly contributing to the development of large-scale RF communication systems.