I'm running sejda, and I'm asking a question here on StackOverflow as that project's support page recommends.
I'm merging a set of PDF documents together, and output either Letter size pages for US readers, or A4 size pages for European readers.
Is there a way I can specify the page size in the XML config file or with a command-line option?
Unfortunately no, the page size for the merged output PDF file is not configurable at the moment.