A small flake should pop off. You then flip the point over and use the new platforms to remove another flake. It takes practice to develop the right combination of downward vs. outward pressure when using this technique, and breakage is as likely to occur as in the conventional style of notching. Having a thin base is also as important as in the other method. The best tip for this style of notching is one shaped like a screwdriver tip.
Force is applied on the edge.
As in all aspects of flintknapping, I'm a strong advocate of reading books. I highly recommend this one too. It is available from the University of Texas Press, PO Box 7819, Austin Texas 78713-7819. Videos are fast becoming a nice way to learn also. This video also shows both types of notching that I just described.