You can add a PDF attachment while creating a sales receipt. To add an attachment, you need to follow the below steps.

1. Click on the '+' sign to generate a sales receipt.
2. Below' terms and conditions, there is an 'add attachment' option.
3. Clicking on the attachment option, you must select the file you need to add.
4. Click open to add an attachment. 
5. Click on save for creating a sales receipt with an attachment. 

Note: Attachment supports only PDF documents.