If you dance the Open Reverse with the Lady in line, then the third step for man will be LF back, left side leading; but with the Lady outside, the shape is quite different, with LF back in CBMP, keeping the body very much in its position from the preceding step (to maintain good contact with partner), before taking RF back with CBM.
Step one of a Back Corte should be danced LF back, left side leading, but if the precede was something like a Rock on RF, it is not uncommon to see dancers straighten up (not more than square) for the LF back into the Corte, before taking the L side back again (through use of CBM) on step 2. This style is not strictly correct, but makes for a variety of shape, and dances well enough.