Go into your profile to the bottom where the box you put your sig stuff in is. In from of the http, put [ L= My Rig ], after the end of the URL, put [ /L ]. Just don't use spaces like I did, for example, between the [ and the L.
Another example of how your sig box should look in your profile is:
{L=My Rig}http://www.anandtech.com/mysystemrig.html?id=15092{/L} <-----------(see no spaces. )
Just use [ instead of {.