First turn the head lamp on by turning the dial on the rhs side of the dash board then to turn the fog lamps in pull the same dial up once for the front fog lamps and twice for the both front and rear. When both front and rear fog lights are on u will get the symbol/icon on the speedo console. With only front on there is no icon.
Yes true,i did tested these but i always find the headlights sufficient enough for me. So i always switch these off. Rear fog lamps does enhance the visiblty in dense fog.