A radio frequency heating apparatus (100) having a cooking cavity (112) dividable into at least two sub-cavities (116, 118), a removable partition (114) for thermally insulating the at least two sub-cavities (116, 118), a rail (128) provided along a boundary of the cavity (112) for supporting the removable partition (114), and at least one radio frequency generator configured to transmit radio frequency radiation into at least one of the at least two sub-cavities (116, 118). The rail (128) is corrugated with a set of grooves or ridges (138), and a perimeter of the partition (114) is corrugated with a set of grooves or ridges (136) complementary to the grooves or ridges (138) of the rail (128).