First, process raspberries, orange juice, lemon juice, and SPLENDA® Granulated Sweetener in a food processor or blender for 30 seconds, stopping to scrape sides down. Pour mixture through a wire mesh strainer into a bowl, pressing the back of a spoon against the strainer to squeeze out juice. Discard seeds and pulp. Stir in orange zest.
Pour mixture into an 8-inch square pan; freeze 8 hours or until firm.
Remove from freezer and let stand at room temperature 20 minutes. Spoon mixture into serving dishes. Garnish with strips of orange rind, if desired.