when you say "right to it" what do you mean?? if you mean the cider..yeah you can stir it right in and taste it...until you have it the way you want..or you can dissolve it i some warm water first if you want.
Adding dry powders provide nucleation points for dissolved CO2 & will cause the CO2 to come out of solution quickly: making it foam all over & sometimes erupt like a volcano. Best to add dry powders to some boiled & cooled water to dissolve them before adding to your must/wort. Regards, GF.