Kilt pins (or any pin) don't need to damage the fabric when pinned in place. Be sure the point is sharp and smooth so it doesn't snag the threads when it goes in.

When pinning be sure to pin so the threads are not split and that the threads are moved aside to allow the pin to go through. If the pin is sharp and smooth if it does split the thread it won't tear the fibers when going through.

I sharpen my pins with my pin cushion. It looks like a tomato with a strawberry attached. The strawberry sharpens the pins when you poke it several times.

Mark