Yes you can Lajos, but you have to make sure that your ESC doesn't have a built in BEC. If it does, you will need to remove the power supply wire from the ESC to the rx. Look in the instructions that came with your ESC to determine which wire to disconnect, but it's usually the red wire. Then you can connect your rx battery pack to the rx in the batt slot.
Your power switch will still go between your rx battery and rx, just like on a gas plane. Just remember to disconnect your battery pack from ESC BEFORE you turn off the rx switch, otherwise your motor might run if you don't have your signal interrupt setting to throttle off.

I have 2 planes that I fly with this configuration, but both of my ESC's in those planes are Opto only, meaning no built in BEC.