Let say when eating with someone, if I wanted to ask him/her: "have you eaten enough?", can I say “十分でしか”? Thanks.
十分でしか is plain ungrammatical; it must be a typo for either 十分ですか (present tense) or 十分でしたか (past tense). I believe both of these are correct and natural ways to say "Have you eaten enough?", but they are used in a bit different situations.
When you ask "Have you eaten enough?" to someone who is still eating, and when you can order/serve extra food if necessary, (もう)十分ですか would be the natural choice.
When you ask "Have you eaten enough?" to someone who has just left a restaurant, for example, 十分でしたか would be the proper choice.
十分ですか/十分でしたか lack the verb "eat", so it works only when the listener can understand from the context what you are talking about, of course. There are many other ways to say something similar. See chocolate's answer.