From what I can tell, you can't specifically share (or bookmark) a link and specify one skin or the other. You can if you copypasta to your own browser (you can see a hash in the URL at that time) but this compares against the cookie on your PC to pick the skin. If you pasted into another browser, the board default would appear. That being said, IP.B used to use something called "lo-fi" option which would actually generate a separate URL that always showed a skin very similar to the IP.Mobile skin. Unfortunately, I haven't seen any current IP.Board use that option, so I am not entirely sure it even exists anymore.