RSSI value of xbee series 2 pin

hi, does anyone know how to read the RSSI value of the xbee and how does it read the RSSI using arduino? i am doing a project that need to use 2 xbee and 2 arduino uno board where the arduino is able to read and detect the signal strength between both xbee modules. is there any website that i can use as reference? thanks! sorry i am noob here =(