On the domain page, go down to the Advanced Tools section.
Click Manage next to Advanced DNS Records.
Click +Add Record.
Here you will add the TXT record:
Type: TXT
Refers to: Select Other Host, then enter _dmarc
TXT Value: "v=DMARC1; p=none; rua=mailto:rua-import-xxxx@sendforensics.com" [Notes: replace rua-import-xxxx@sendforensics.com with your own unique SendForensics RUA processing address which can be found in Domain Settings for your domain.]
TTL: 60 (1 minute - so that you do not need to wait too long before verifying)
Click the Add button.
Wait for a few minutes, then you can verify that you have the correct record entered in Domain Settings for your domain.