Very generally speaking, a nice sporran with a cantle is probably fine for semi-formal wear, though I didn't follow th elink to that one.

I always wear a belt with my kilts, but that' s just because I'm a slave of habit and I always wore a belt with pants, too. No belt makes me feel incomplete, so....

But hell. As long as the thing stays on and you don't look like a shortbread tin after a bad LSD flashback, wear what you want!

Oh, ansd welcome to the joint, too...