How do I attach a PDF document to my turbotax netfile return?

[TurboTaxSusan]

You can't add any attachments using TurboTax.

Generally, when you file online using NETFILE, you don't need to send any other documents unless the CRA requests them. At that time they'll let you know how they want you to get the documents to them, but usually you can send them by mail or through My Account.