Here is a link to a photo of the backs of a standard Scottish-made sporran (left) and an American-made Buzz Kidder sporran (right).

http://www.xmarksthescot.com/photoplog/index.php?n=171

The sporran on the left has a wide loop sewn to the back so an all-leather belt can be threaded through it. A small leather strap with a metal ring on each end is provided to allow the attachment of a leather and chain strap with clips.

The sporran on the right has two narrow loops riveted to the back for use with an all-leather belt. There is a metal ring located at the top of each loop for use with belt that has clips.

I hope this helps.