When you send a document for signature, you can associate the document (or packet of documents) with a transaction. Once those documents are fully signed by all parties, they will automatically appear in the File Cabinet of the transaction. From there, you can attach them to your checklist for the transaction.
If you haven't created your transaction at the time of sending the document, you skip the step to associate the document with a transaction. Once the documents are signed, you can download them from Real Signature and upload them to your Checklist.