Sheepskin covers headrest holes?

[Will.iam]

Just installed my new sheepskin seat covers and noticed they do not have holes for the headrest bars to go through. What do you use to make the holes? A slit with a sharp knife? A drill bit? A hole punch? Would hate to make a hole and have it continue to open up with strain of people sliding into the seat.  

[Schllc]

I used a knife point on mine and flew for years without issues. 
the material for mine was fabric backed leather. I don’t think running will be an issue if yours are made the same. 
aerosheep sold me mine. 

[PT20J]

You might look for a leather punch in the correct diameter.

[bradp]

Hole / leather punch on a proper backing.