Rice flakes have no enzymes to self-convert. You're not producing sweet wort, just transferring some long-chain carbohydrates to the liquid. Your end consumer will be using this as an adjunct to malted barley; they do not expect this to convert on it's own.
I highly recommend NOT adding alpha amylase. Again your end consumer will be using this as an adjunct to other grains, malted grains, and the addition of alpha amylase would cause a lot of brew calculations to be missed. It would also add a great deal of confusion, as nobody would ever suspect a manufacturer would be adding AA to any of their grains.