The reason that a nail looks fan shaped is because the eponychium is small, so therefore the lateral folds come out in a 'V' like shape.
This gives the illusion that the nail grows wider the longer it gets (which is not the case).
The most important aspect of doing a fan shaped nail is to make sure that you avoid a Square extension edge as this will emphasize the illusion that it grows wider the longer it gets. You are far better suited to go for a tapered oval extension edge.
So, use whatever tip fits (based on C-Curve) and make the nail more oval