After some searching around, I've not been able to find butterscotch extract in any nearby stores. I suppose I could order online, but I've realized that there is quite a bit of butterscotch syrup floating around. If I get one with no fat could this cause any problems? I notice that this stuff tends to have some preservatives in it, but I've heard that that isn't always a problem.
Can I put this stuff in during the boil and expect to have a reasonable beer at the end? I'm aiming to still have a nice foamy head at the end.