Radio button fill options

If you create your forms layout along with form fields in Apache OpenOffice.org Writer or Libre Office Writer then one can save the document as a PDF form with the PDF forms present in the exported PDF form.

You can't change the way the wizard works, but you can edit the fields after they're created and change their check style from Square to Cross, Check or anything else. You'll find this option under Properties - Options tab. You can select multiple fields and edit all of them at the same time.