I remember when i was little i went to a cookie decorating party, and for the gingerbread they had lemon flavored RI. I got some lemon flavoring at whole foods and realized after i opened it that it was like lemon oil. will that mess up the RI? i know that grease and RI don't go well together.... any help helps!
AI would be worried about using it. Some alcohol based lemon essence might be a better option.
Just use fresh lemon juice instead of water!
I second the fresh lemon juice suggestion. I made some lemon-flavored sugar cookies last year for Christmas (snowflake shaped cutouts) and iced them with white RI with fresh lemon juice in the icing. Tasted very lemony and hardened up nice.