The optional Extras block is used to apply stamps to the body of an appended document. You can add a watermark, company logo, page numbers etc. Extras stamps will not be applied to Cover or Table of Contents pages. One stamp file can be used in the Extras block. There is no limit to the number of stamp items in the file. Stamp Files provides full instructions for creating stamp files.
Cover pages, Table of Contents pages, and appended pages each use an independent stamp file. Stamps listed in the Extras block are to be applied solely to the appended pages of the output PDF and will not affect the cover or TOC pages.
The Extras block in your parameter file is constructed as follows:
As with the other parts of the parameter file (except for the Source Files Block) make sure there is at least one space or tab separating the keyword StampFile from the value in parentheses. The extras block must begin with begin_extras and end with end_extras.