Please follow the procedure below to convert an existing PDF form into a fillable PDF form with Adobe Acrobat XI or Adobe Acrobat X Pro:
  • Open your Adobe Acrobat XI or Adobe Acrobat X Pro.
  • At the top right in Acrobat, click the Tools pane.
         
  • Click Create.
         
  • Select "Use an existing file" and then click Next.
         
  • Locate your PDF document to convert by choosing either "Use the current document" or "Import a file from file system", and click Next.
         
  • Acrobat analyzes the document and adds interactive form fields. Inspect the form fields list in the Fields panel. You use the form names when collecting and analyzing data, so make sure that each name is unique and descriptive. To change a field name, double click and type the desired name in the General tab. Click close.
  • To edit fields, select the field and click Edit in the Tasks panel. You can also add fields.
         
  • At the top of the Forms Editing toolbar, click Preview (This button toggles between Edit and Preview.) to display the form as a recipient will see it and to test form behavior. To return to editing mode, click Edit.
         
  • When finished, at the top right in Acrobat, click the Close Form Editing button.
         
  • Last but not the least, save your PDF form by clicking File and then clicking on either Save or Save As.