The federal trademark registration symbol is an encircled “R.” For example, Coca Cola®. Only registered trademarks may use the ® symbol. Use of the ® symbol on a trademark specimen for an unregistered trademark application will typically cause the USPTO to refuse to accept the trademark specimen as proof of use. Prior to registration, it is permissible to use the superscript TM symbol (™) or the superscript SM symbol (for service marks).