Making a Riving Knife

My panel saw doesn't have a riving knife or blade guard attached! I have the guard but need to make the knife to hold the guard. I would be interested to find out the thickness of some riving knifes out there if any one has the time to run a vernier over their saws riving knifes...

The other thing is if i make a knife that's thin enough say 1.8 or 2mm for using with thin kerf blades 2.2mm will it offer enough or any kickback protection when using 3, 3.2mm thickness blades?

Thanks in advance

Dave