[en] The property of reversed-field pinches (RFPs) to relax to a near- minimum-energy state is the basis of oscillating-field current drive (OFCD), wherein plasma current is driven by modulating in quadrature the external toroidal and poloidal magnetic fields. Coupled plasma/circuit OFCD simulations of RFPs ranging from present experiments (ZT-P and ZT-40M) to the reactor (TITAN) indicate that the drive frequency and the amplitude of the plasma-current oscillations decrease with decreased plasma resistance so that minimum frequencies (/approximately/25 Hz) and plasma-current amplitudes (/approximately/1.6%) and maximum efficiencies (/approximately/0.3 A/W) are attained in the reactor regime. Methods for minimizing the reactive powers and for optimizing the current-drive efficiency for OFCD in RFPs have been identified. 15 refs., 4 figs., 1 tab