When setting up your import file, you can denote whether or not checkbox and radio button fields should be selected.
To mark a field as "checked" or "unchecked" you can define the field using the below terms:

TIP: A blank is counted as unchecked, but won't overwrite a previously checked field.

For Example: In the below file, all of the email addresses that were acquired in-store have the designation "on." The corresponding radio button in Listrak will be checked.