How can I send a transmittal document to be signed and tracked with an attached large document not to be signed?

We send large (many times 300+ page) reports out to various outside organizations. We create a one page transmittal document for the recipient to sign and return to us stating they have received the report. When I have placed the transmittal into the "Send document for signature" after placing a signature field at the bottom and then "add a document", the report pdf, either I get an error that the pdf is over 100 pages and cannot be processed or the system adds a signature to the last page of the report.

I want to have the transmittal only tracked and signed but need the added document attached with no signature required. I cannot find any answer to this in the user guide. I'm within my first 14 days and will need to cancel this subscription if I cannot get this issue solved.