To set RV leveling blocks, position the RV 2 feet away from its final stopping point, turn off the engine and set the parking brake. Place a block against each tire to stop it from continuing in the direction it's going.
Start the RV, release the parking brake, and engage the transmission to allow the engine to roll the RV up to the block and stop in the middle of the block. Work with someone outside of the RV to be sure the RV is directly in the center of the blocks. Verify that the RV is level. Always keep one tire firmly on the ground when using leveling blocks.