Welcome to the Community, lpezet.
I'd be glad to help out so you're able to attach a copy of a receipt to the invoice.
This can be done by:
1. Clicking the Create Invoices button.
2. Enter the necessary info.
3. Select Attach File at the top of the invoice window.
4. Choose the file containing the image of the receipt.
5. Click Save & Close or Save & New.
This article provides additional details about the QuickBooks Document Center: FAQs and common issues.
You may also want to check out this link that tells how to upload scanned images with the QuickBooks Scan Manager.
That will do it. I'm only a comment or post away if you have any other questions.