This is something that has been bothering me for years.  I've seen quite a few fakes, so I thought I'd share.

If you like Stargate SG-1, or MacGyver, or Rick in general, please note that he ALWAYS signs his name RICHARD DEAN ANDERSON, never Rick Anderson and never in cursive.  His autograph is all block letters, and very legible. 

The reason for this is because there are a couple other Rick Anderson and Richard Anderson's out there in the acting world.  So, if you see it signed 'Rick Anderson' be careful.  It's probably a fake.