First, it is not horrible. Pop one of them out in front of a real person and they will be thrilled. So - good start.
Here's the secret: The pressure fan is finished with the right fingers - not the right thumb. It's a weird thing to try to describe, but as you get to the end, the right thumb tip rolls upward. It is still contacting the cards - but the BACK of the cards, not the ends. You maintain a downward pressure for control purposes, but by this point, it is the right fingers that are really doing the work.
The right thumb ends up laying on the back of the decks top cards and UNDER the left thumb.
Also, don't think of the right hands movement into the fan as a semi circle. Think of it as an upside down 'U'.
Did that make sense at all?
Brad