It may also take the RFC card - since Rain Forest Cafe and Yak & Yeti are both owned by Landry Food Corporation.
At RFC you get a free appetizer with the RFC card.
Just a thought, no guarantee
Yak & Yeti® - Disney's Animal Kingdom® Theme Park
Dine with 10% off the regular price (excluding applicable tax and gratuity) of lunch and dinner entrées for the Passholder and up to three Guests. Discount excludes alcohol and is not valid at Yak & Yeti's Local Food Cafes.