How to combine|merge multiple PDF files into a single file via itext pdf java lib?

Is there some way to detect the page size and then use that same page size for those documents? Or, if not, is it possible to have it fit to page?I would like to add a link to an existing pdf that jumps to a coordinate on another page.I have the following problem when printing the PDF file after m

Merge PDFs with iText’s free online app and sandbox.