Radio frequency (rf) power is commonly applied to the chuck of a high-density plasma reactor in order to extract ions and to control the energy of the ions used for the fabrication of microelectronic devices. In many cases, the temporal shape of the rf wave form largely determines the shape of the spectrum of those extracted ions, thereby strongly affecting feature evolution. Using auxiliary rf circuits, we successfully made major changes to the rf-potential wave form at the chuck of an Applied Materials 5300 HDP Omega reactor without affecting the normal functioning of the reactor's control systems. This work established the practical feasibility of techniques for modifying the ion energy distribution functions of industrial reactors.