A radio-frequency (RF) heating system may include a removable drawer, which may be inserted under a fixed shelf of the RF heating system to form an enclosed cavity. The drawer may include conductive channels or side rails that may interface with the shelf of the defrosting system in order to electrically couple the drawer to the RF heating system. The drawer may include an electrode that is electrically coupled to ground or to a RF signal source when the drawer is inserted beneath the shelf. The shelf may include selectable electrodes of varying sizes. The RF heating system may use identification circuitry to recognize the type of drawer that has been inserted beneath the shelf. RF energy may be applied to the electrode of the drawer or the shelf to heat a load in the enclosed cavity.