For more information on macro viruses, see the description of WordMacro/Concept.
Mtf is a an extremely simple macro virus which only spreads. The name of the virus comes from a macro it contains: Mtf1.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.