A self-consistent method is described for determining the static magnetic-field reduction in a magnetized plasma with a specified density profile by radiofrequency (rf)-driven rotating magnetic fields (RMFs). Electron-ion collisions and transport losses are included in the analysis. Application of RMF current drive to tandem mirrors and rotomak reactors is considered. The results of the calculations show that magnetic wells can be produced in mirror configurations, and reversal of applied static magnetic fields can be generated in rotomak geometries by RMF for modest investments of rf power at frequencies for which the rf technology is economically attractive.