How do I keep a pdf copy of paid check to submit for reimbursement

I pay vendors from my own accout and then get reimbursed from the servicer. I have to upload the proof of the payment to thier portal. I do not want to scan every single check that I write, that is one reason I bought quick books. But I do not know how can I save the copy of check as pdf so I can use as proof of payment (of course wihtout scanning the printed check) to upload to the vendor.