Employee Referral App Flow - submission level fields

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I'd like to use a couple submission level fields for the employee when going through the referral application flow to refer a friend. We want them to check a box every time they submit a referral that says "Yes, I know this person and they know I'm referring them" to keep someone from spamming the program with every email they have ever known.

Doesn't seem as though I can do that as submission level forms never show up in any of the choices when I go to use a form for a block. Support is still looking into it, but they don't seem to know either, at least off hand. Any one try to do this?