Drilling holes in vinyl fence posts???

Get your nipples all hot and bothered and just press'em against the post. :)

Use a bit with the small points they don't skitter at all just start off slow then drill. Should go thru like butter I have the Dewalt set not cheap but high quality

Stick a piece of masking tape over the area to be drilled then drill through that. The tape will stop the drill from skidding.

sPoNiX

Get some "brad point bits" which have a center spike, and cutters around the outside. They are used in wood working, and drill a flat bottomed hole (almost), with no taper.

You should be able to get a small set (like 10 bits) for like $10 at the HW store.

Otherwise, punch or burn a small dimple, like what is done with metal. A pin and a lighter comes to mind, it should be enough, heat the pin and stick it where you want the hole, pull out, drill hole.

Beats me why what you suggest would not work. Have you tried the method and it failed?

If it does you could always get a 1/16 bit and make a pilot hole.

Works great on wood, metal, plastic, ...

I have 100 4x4 PVC fenceposts with field fence and electric fence insulators top and bottom. I used self tapping coated screws to secure the insulators. Bead_runner