I would recommend not spot feeding a BTA, from personal experience. Not that I had anything negative happen, but just that they will do perfectly fine without being spot fed.
Instead, I would recommend “feeding the tank”, so that if the nem is hungry it will grab any food floating around - this will obviously feed your fish/coral too. I use NanoReef Frenzy and everything love it.
Recommend doing this once a week, no real reason to do it more.