SANTA MONICA, Calif.--(BUSINESS WIRE)--Tapstone (www.tapstone.com), the proven media buying agency and optimization platform, today announced that it has added Direct Response (DR) Radio to its campaign offerings for DR advertisers. Every month, the company purchases over 1 billion impressions; delivers over 4.5 million clicks and 25 thousand leads, sales and website registrations. The agency expects its reach to continue rapid growth as its unique approach to omni-channel DR advertising gains