After reading several other posts in the forum I understand that it should be possible to set up a form that allows for both a one-time fee and recurring fees with Authorize.net, and that they just need separate feeds pointing to the same form in order to work.
I have set up my form here: https://www.topdawgpetsupply.com/pet-store-gold-test/. We just have dummy pricing in there for right now but the basic gist is we want the form to charge for the Gold Package setup fee and first Monthly Fee as a one-time charge. On page two of the form, we also give the user the option to add on Monthly Web Services and Monthly Email Services. On the final page I created a Calculation product field called Future Monthly Fees, which is the monthly fee plus the add-ons.
On the Authorize.net feeds, I currently have one set to Products and Services, linked to this form. In running test transactions, this feed is working properly and payments are processing.
I also have a separate Subscriptions feed linked to the same form. The field selected for the Recurring Amount is the "Future Monthly Fees" Calculation field. The settings for this feed can be seen here: http://imgur.com/tcyOYVN. We've run several transactions now, and our client has said that each time, nothing is happening in the ARB section of their Authorize.net account - no record of transaction (which there shouldn't be since the first billing should not be for another month), but also no account/transaction set up for future billing.
Is there something I'm missing? The client confirmed they have ARB turned on (they've been using it for years with another site). Do I have one of the settings off, or could it be that you can't set up a recurring payment based on a Calculation product field? Any help would be appreciated.