Go to your Domain List and click Manage next to the domain:
Select the Advanced DNS tab:
Find the Host Records section and click on the Add New Record button
Select NS Record for Type and enter the Host you would like to point to a server:
For Dynamic DMARC enter: _dmarc
For Dynamic DKIM enter: _domainkey
Enter the Value of the Name Server to point to:
For Dynamic DMARC enter: ns-dmarc.ondmarc.com
For Dynamic DKIM enter: ns-dkim.ondmarc.com
Check the Save All Changes button once done:
Create a free OnDMARC account to test your configuration.