Autoline has the option to attach PDF documents to Purchase Ledger transactions.
When in Batch Input or Invoice Register click on the Scanned field and there will be an Attach option (if this option does not appear please contact Systime Support to have it added)
Clicking the attach option will allow you to search for the PDF on your PC
Select the document and post the transaction and you will be able to view or print it from the PL or NL in the same way as Point of Sales invoices.