The precursor of arcs in radio frequency heating systems, namely corona discharges, are examined numerically in this paper, using the finite element-flux corrected transport technique. A point-plane configuration is used as a first approximation for a radio frequency applicator and the effects of the operating frequency and pressure on the current output, charge densities, corona onset voltage and light output are investigated. It was found that an increase in the operating frequency around the radio frequency part of the spectrum, resulted in an increase in the corona onset voltage, which accounts for the less arc-prone behavior of microwave systems. Also, a decrease in the pressure resulted in a reduction of the corona onset voltage, and thus the increased possibility of arc formation in radio frequency systems operating under vacuum conditions.