Hi,
I use earthworms as a staple for my ACFs. They are usually fed twice a week (all are adult, so I sometimes skip a week when I´m on vacation). The females eat about everything, including pellets; the male is more picky and constantly refuses to take them. As long as it isn´t a problem for you to feed them live food, your frogs will be fine without pellets. While Reptomin pellets seem to provide about everything an ACF needs, it´s no must

If you still want your frogs to to eat Reptomin, I would recommend fasting them for about a week and then feed nothing but the pellets until they reliably accept them. As long as they get more appealing food, they probably won´t go crazy about pellets. Possible leftovers should be removed after about an hour.