Green coffee cider

[macachoin]

I'm thinking of trying to add Starbucks green coffee extract as a bitter and nonfermentable sugar to a cider batch this fall and I was curious about ideas regarding the amount I should add? For the drink you use 1 pouch per 16oz. so I was thinking 4 pouches in a 1 gallon batch of hard cider as I don't want to overpower the apple flavor? What are other opinions? The nonfermentable sugar is stevia and I've heard of varying success/non-success with using it? Any suggestions are appreciated!!