How to Add a Registered Trademark Sign on Twitterby Ryan Menezes
Twitter offers no specific tool for adding special characters -- or, for that matter, adding any characters at all. You just type your tweets using your computer keyboard. When you have to enter a character not on your keyboard, such as the "®" registered trademark sign, you can copy and paste the symbol from another Web page. If you often include the trademark sign in your tweets, consider memorizing your computer's Unicode shortcut for the symbol.
Sign in to Twitter, and then click the box labeled "Compose New Tweet."
Press "Num Lock" on your keyboard if Number Lock is currently disabled to enable your number pad.
Press and hold the keyboard's "Alt" key.
Type "0174" on your number pad to add a registered trademark sign.