here is a little help how I did:
<pre>
<?
$pdf = pdf_new();
pdf_open_file($pdf, "/tmp/test.pdf");
pdf_set_info($pdf, "Author", "Horvath Tamas");
pdf_set_info($pdf, "Title", "Szamla");
pdf_set_info($pdf, "Creator", "ARBOMedia.net Kft");
pdf_set_info($pdf, "Subject", "Szamla");
pdf_begin_page($pdf, 595, 842);
pdf_add_outline($pdf, "Page 1");
pdf_set_font($pdf, "Times-Roman", 30, "host");
pdf_set_value($pdf, "textrendering", 1);
pdf_show_xy($pdf, "Hello world", 50, 750);
pdf_moveto($pdf, 50, 740);
pdf_lineto($pdf, 330, 740);
pdf_stroke($pdf);
pdf_end_page($pdf);
pdf_close($pdf);
pdf_delete($pdf);
$len = filesize("/tmp/test.pdf");
header("Content-type: application/pdf");
header("Content-Length: $len");
header("Content-Disposition: inline; filename=test.pdf");
readfile("/tmp/test.pdf");
?>
</pre>