OK. Hold the plug so the prongs face you, and the hole for the cord insertion faces away from you. My drawing shows the wider brass prong on your left, and the smaller on the right. Hold the cord as if to insert, so that the side with the ink on it is on the top, and will match up with the left hand wider brass prong.
Hope that corresponds with the written instructions, and is clear. I realize my drawing shows left - I'm not sure how they want it oriented for L/R (maybe holding the plug as if to plug into a wall), but I've put more than one Reptile Basic RHP plug and wire together using that drawing.