Creating PDF files with PHP

I'm trying to create a pdf file, on the fly, using php.

Everything seems to be working except the text - I'd like to be able to display text in hebrew.

Here's my code:

pdf_open_file($pdf, "SupplierPE/$filenam");
pdf_set_info($pdf, "Author", "company");
pdf_set_info($pdf, "Title", "pdf file");
pdf_set_info($pdf, "Creator", "company");
pdf_set_info($pdf, "Subject", "pdf file");

pdf_begin_page($pdf, 595, 842);
pdf_set_parameter($pdf, "textformat", "utf8");
pdf_set_parameter($pdf, "FontOutline", "ArialUnicode=ARIALUNI.TTF");
$arial = pdf_findfont($pdf, "ARIALUNI", "host", 0);
pdf_setfont($pdf, $arial, 14);

list($width, $height, $type, $attr) = getimagesize($HebLogo);

if($type==1) $gif_image = pdf_open_gif($pdf, $HebLogo);
else $gif_image = pdf_open_jpeg($pdf, $HebLogo);

$left = (575-$width);
$top = (822-$height);

pdf_place_image($pdf, $gif_image, $left, $top, 1.0);

pdf_close_image($pdf, $gif_image);

$left = ($left - 100);
$top = ($top - 10);

pdf_show_xy($pdf, "$HebTitle",$left, $top);

pdf_end_page($pdf);
pdf_close($pdf);


The font files are in the same directory as this script.
The variable $HebTitle contains text in hebrew and when the pdf file is created, it only displays jiberish.

Can anyone please help? I'm sure it has something to do with the unicode setup, but I'm not sure how to fix it.