if u have a registered trade mark you use the (r) if you just want to have a tm next to your name you can... it really doesn't mean much, if someone steals ur mark and you can show u have proper rights to the look/feel of the (graphic) you can make a case... not an issue otherwise.
@ www.tapinko.com we have a registered trademark with the USPTO so hence we put up the (r). It also helps with international law, etc... but proof it is on record.
