NetSuite SS2.0 - Create a File with "addtimestamptourl" checked

Looking here for a way to set the GENERATE URL TIME STAMP field (addtimestamptourl) to checked using SS2.0 as part of rendering a PDF.

Currently I have:

var fPDF = renderer.renderAsPdf();
fPDF.name = fName;
fPDF.addtimestamptourl = true;
fPDF.folder = fFolder;
var fileId = fPDF.save();

I have also tried

fPDF.addtimestamptourl = 'T';

With no success so far, the box remains unchecked on the file record.