maybe I miss understood you...
You want to print PDF's not print to a PDF ?
If that being the case, you can use the ShellExecute(0, 'print', PathNameOfPDF, '',SW_HIDE);
The last one I may have wrong, made..
Do this in a loop and using the list of names you have... It should all go to the Printers que with the currently selected printer.
Of course if you want to do all of this inside your app and especially trying to make this cross platform then maybe we need a PDF viewer in laz that we can print from.