FlexiPDF not only enables you to complete forms, but it also allows you to create new forms with interactive buttons, checkboxes and other form elements (only in FlexiPDF Professional and FlexiPDF NX Universal).
These new forms can then be completed with FlexiPDF or another PDF viewer. The form values can be exported to XML format for further processing.
Completing existing interactive forms
To complete an existing interactive form, enable the Hand tool 
and then click on the fields in the form.
You can let FlexiPDF highlight all interactive form fields in order to see them better. To do so, choose the ribbon command View | Shade form objects (in the group View). If there are no interactive form elements on the current page, this option will be grayed out.
Creating your own interactive forms (available in FlexiPDF Professional and NX Universal)
You will learn how to create interactive forms in the following sections: