If your talking about retics as I am assuming you are since this is in the retic forum, then definitely feed inside the enclosure. Once they reach adult size feeding outside of their enclosure can not only be a pain in the ass but also dangerous. Most retics feeding response's are insane and you don't want to have to deal with an adult retic in feeding mode outside of it's enclosure unless you absolutely have to.
It's a good practice (at least in my opinion) to hook train retics from babies. Whenever you get into the enclosure for any reason at all besides feeding touch the retic with a hook. When you go to feed him never let him see a hook. Soon he will recognize that when touched with a hook it is not feeding time.
This is what I do and it seems to work very well.
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Bill