3.
(Optional) To test the form you are previewing by using a data source that you created, enter the full path to your test data file in the Data File box. You can also use the browse button to navigate to the file.
4.
(Optional) To test the form you are previewing by using an automatically generated data source, click Generate Preview Data. You can use the browse button to navigate to the location where you want the file saved. If the form contains repeating subforms or subform sets, indicate the number of times each subform or subform set will repeat in the data file.
See also 

To set preview options for an interactive form