setPosition('bottomleft');

//Place watermark behind original PDF content. Default behavior places it over the content.
$watermark->setAsBackground();

//Specify the path to the existing pdf, the path to the new pdf file, and the watermark object
$watermarker = new PDFWatermarker('C:\test.pdf','C:\output.pdf',$watermark); 

//Set page range. Use 1-based index.
$watermarker->setPageRange(1,5);
 
//Save the new PDF to its specified location
$watermarker->savePdf(); 
?>