In this tutorial I will explain the simple way to add SPF Record for our domain in WHM/Cpanel.
- Login to the WHM/Cpanel as root or with the administrator owner
Go to the WHM >> DNS Functions 
Choose the zone we want to edit, and Click Edit
- At the empty text box , Add New Entries Bellow This Line, fill it with the example :
For example my domain name is erawanarifnugroho.com, then it should be likt this :erawanarifnugroho.com.    14400   IN    TXT    "v=spf1 a mx ~all"
- An then click Save
