Mine are kept in a species-only tank, so I have no problems just dropping the food in and leaving it until they find it. When they were in community, I'd hand-feed them or use a turkey baster or oral syringe to get the food directly to their mouth. Some people on this board also use tweezers, or feed in a specific area - like a cup or a dish, or in some other way target-feed them. As long as you're aware that there could be a problem, and pay enough attention to ensure that the frog is eating their share, they'll be fine. Adult frogs (older than 9 months) only need to be fed every other or even every third day, and they're very quick to catch on to whatever method you use to feed them. Smart little buggers!