You don't need to drill holes. I would NEVER drill holes in a car.
Use SIKAFLEX to attach it to the boot lid.
I added the VE G8 boot lid spoiler much like yours for your VF to my VE in 2009 using SIKAFLEX and it's never moved.
Clean boot lid with PREPSOL, clean spoiler with PREPSOL. Wipe off with a clean cloth.
Run a bead of SIKAFLEX onto underneath of spoiler holding it upside down, where it touches the boot lid.
Use two people to place it very carefully into position.......You might do as I did and make a couple of lead pencil marks to be sure it correct.
Hold it down then tape it down with masking tape and leave it for 24 hours or more.
All too easy and quick with no holes drilled that will go rusty in time and look very ugly.