Artist Point, Narcoosee, Citricos, California Grill, CRT, Brown Derby, Flying Fish, Yachtsman Steakhouse, and Jiko all accept the
DDP and are two credits. The dinner shows (Hoop de Doo, Mickey's Backyard BBQ, and the Luau) are also two credits on the DDP, but are not Signature dining.
However there are some restaurants that Disney lists as Signatures that only accept the Platinum or Premium plans (Fulton's and Victoria and Alberts). Also none of the restaurants at the Swan/Dolphin accept the DDPs, so that would include Blue Zoo, Shulas, or Il Mulino. You can't use the DDP at any of these.
You didn't ask, but alot of people wonder if since the Signatures cost 2 credits do you get more. No you don't. If you are on the basic DDP all you get is an entree, dessert, and nonalcoholic beverage. Wait a minute, let me correct that. At Artist Point, if you are on the DxDDP you do get to choose an extra side from the items listed on the bottom of the menu. I believe they just started that this past year though, as we never have in the past.