Regarding Craig's suggestion: "However, maybe there is a simpler solution. Doesn't just saving a FM file as a PDF using File>SaveAs Review PDF>Enable Commenting in Reader accomplish what is wanted? If saved that way to begin with, there is no need to batch the resulting PDFs. Someone more familiar with Extendscript than I might also comment on the feasibility of using that to operate on a series of FM files in a folder to accomplish this SaveAs function."
This is exactly how I create a PDF for review. Reviewers can highlight, comment, etc., then save the PDF with their comments. Susan