In addition to creating Text fields, you can create Checkbox or Radio Button fields in PDF templates. To create Checkbox or Radio Button fields in PDF templates:
On theCheck Box.
Use the standard field naming conventions.
In the Check Box Properties, enter the Field Name from the Template Builder on the General tab.
In the Check Box Properties, define the True or False value that indicates when the checkbox field should appear selected in the Export Value field on the Options tab.
The Export Value for Salesforce Checkbox fields must be either True or False.
You must have at least 2 radio button fields (both referencing the same merge field name) in order for the value to appropriately merge to the output.