You can generate sample data to preview and test your form instead of creating a sample data file. Also, if your form contains repeating subforms or subform sets, you can specify the number of times the data will be repeated when you preview the form.
LiveCycle Designer ES generates sample data that is valid for the corresponding objects in the form, with a few exceptions:
Specify which data file to use when you preview the form. The next time you preview the form in LiveCycle Designer ES, the sample data will appear in the respective objects.
1.
In LiveCycle Designer ES, select Edit > Form Properties > Preview tab.
6.
In the Generate Preview Data dialog box, type the full path, including a file name, for the test data file. You can also use the browse button to navigate to the location in the Data File box.
See also 

To automatically generate sample data to preview your form