Skin treating devices and systems for delivering RF electromagnetic energy to the skin. The devices include one or more electromagnetic RF generating units, multiple RF electrode groups and a controller for controllably applying RF energy to the skin through any selected RF electrode group or any selected RF electrode group combination selected from the multiple groups. The electrodes may be stationary and/or movable electrodes. Different RF frequencies and/or frequency bands may be used. The alternation of energy application through different electrode groups at different times, and/or the changing of the inter-electrode distance and configuration by using movable RF electrodes may reduce or prevent electrode overheating, control RF energy distribution within the skin and enable use of the devices and/or for different skin treating applications.