fdf_set_file

<?php
  /* set content type for Adobe FDF */
  fdf_header();

  /* start new fdf */
  $fdf = fdf_create();
    
  /* set field "foo" to value "bar" */
  $fdf_set_value($fdf, "foo", "bar");

  /* tell client to display FDF data using "fdf_form.pdf" */
  fdf_set_file($fdf, "http://www.example.com/fdf_form.pdf");

  /* output fdf */
  fdf_save();

  /* clean up */
  fdf_close();
?>