Add Custom Field
Add Custom Fields to a person from their profile in your account. When a Custom Field is added directly to a person, the field only applies to that individual person and no other people on your list will be affected.
To add a custom field to an individual person:
Click People
Enter the person’s email address into the Search by email? search bar
From the person’s profile, click Tags & Custom fields
Click + Add a custom field
Enter the Identifier
Enter the Value
Click Save