Use document size/PDF TrimBox as a label

Hello. I have found the SizeLabels.jsx by Jongware and it's very close to what I want. It is putting a label, but it's using the size of the image in InDesign. I would like it to put the size of the placed file. And in the case of PDFs, put the size of the TrimBox. If I have to choose one or the other...I need the PDF TrimBox size. I am very new to InDesign scripting. Can someone help me please? Thanks.

InDesign CC on Mac OSX Mavericks