no big RETF could ever eat a 1 and 3/4in RETF... for a tree frog, they like their food rather small and aren't considered a voracious frog
Trust me you have nothing to worry about on this one...........!!!!!!!!
No matter what the size is tho, when you bring in a new animal, monitoring behaviors is vital.
What size is your vivarium tho?
I wouldn't put 4 RETF in nothing smaller than a 18x18x24...
24x18x24 would be better for them imo.