Designated Marketing Areas (DMAs) are also referred to as media markets typically in television and radio markets. DMA targeting is typically not used by political and advocacy campaigns because DMA's are very large and often cross state lines - therefore not being a good targeting solution for a campaign in one city or state.
Currently, our geo-targeting options in our self service ads platform are city/state/zip or any district-level targeting for all state house, state senate and congressional districts nationwide.
That being said, if it's something you want to pursue - it is something we are able to configure in a managed service ad campaign. Unfortunately, it's not on the roadmap to offer in the self-serve platform at this time.