Hello @clearviewcompanies
You would firstly need a generator like the one my colleague mentioned above for QR codes. You can simply use @Glenn’s example and update the web address to fit the URL of the generator, which should do the trick.
The post above uses the Invoice ID, which isn’t the invoice number but can uniquely identify the invoice on QuickFile. I found a generator, so adding something like the following should work:
<img src="https://barcode.tec-it.com/barcode.ashx?data=@InvoiceId@&code=Code39&dpi=96">
or
<img src="https://barcode.tec-it.com/barcode.ashx?data=@InvoiceId@&code=Code128&dpi=96">