"-f" is the option to specify the file to be attacked. I intuitively figured I could specify several files in the same attack, but several test showed this wad not the case.
Hence, the feature request would be to simply try the calculated hash against every file passed as argument (not just the last).
Additionally, but not as important, entering by hand the name of each file can be rather...
2008-07-24 20:32:41 UTC in pdfcrack