[en] The preliminary conceptual design is described of RST, a radio frequency driven, steady-state tokamak. The function of RST is to develop the physics and engineering bases for the development of the tokamak as a true steady-state reactor. The physics of rf current drive, using a variety of electromagnetic waves, is discussed. The device makes use of a novel superconducting toroidal magnetic field coil concept, in which the axial current is carried in only three return legs, and superconducting pullback coils are used to reduce the magnetic field ripple. This technique greatly increases access to the plasma. Impurity control by means of edge cooling, bundle divertor, and rf wave momentum sources is discussed, as well as fueling