How to use the External Library TCPDF / FPDF in a form Custom Button

Hi All
I am trying to use the TCPDF / FPDF External Library (included in scriptcase) from within a Form. I have a Custom button (PHP) in Form.
I want to generate a PDF in custom format and as such want to use the external library. The export to PDF is not customizable and hence I am using the Custom Button and routine.
I used the External Libraries / Use Library / Save option.
Then Code used sc_include_library(“prj”, “TCPDF”, “tcpdf_include.php”);
Getting the Following error :
Fatal error: Uncaught Error: Failed opening required ‘…/_lib/libraries/grp/TCPDF/tcpdf_include.php’ (include_path=’.;C:\php\pear’) in C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\app

Next :
I use Save as option to save in Projects. Name used MyTCPDF
I changed the above include command to have MyTCPDF
I am getting the following error
Fatal error: Uncaught Error: Call to a member function SetFont() on null in C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\app

Following is the PDF code in the Custom Button
$pdf = $this->Pdf;
//$pdf->Image({emplogo}, 12, $y + 12, 60, 13,‘PNG’, ‘’, ‘N’, false, 300, ‘L’);

// from printHeader
$pdf->SetFont(‘helvetica’, ‘N’, 9);
//$pdf->SetFont(‘helvetica’, ‘N’, 9);
$pdf->Multicell(80, 5, $end, // w, h, txt
0, ‘R’, true, 1, // border, align, fill, ln
118, $y + 12, true, 0); // x, y, reseth, stretch

Can someone please point out where I am going wrong ?