You might take a look at:

This takes the same approach, but used a batch file rather than ShellExecuteEx:
https://www.appeon.com/developers/get-help/knowledgebase/powerbuilder-printing-pdfs-using-acrobat-reader.html

This lists a number of other options:
https://community.appeon.com/index.php/qna/q-a/pdf-documents-print-option

We use the shellexecute approach, as you do.  As you may have noticed, Adobe leaves an empty minimized reader around after you do a print.  That's why the solution first link above kills the Adobe Process when the print is completed.

Looks like the problem my beta tester has is that last time he used Acrobat Reader, he printed to pdf instead of printing to a printer.  Acrobat somehow remembers the last Print option used. When printing from my app, Acrobat will ask where to print the file... 

Can you check this thread 

https://community.appeon.com/index.php/qna/q-a/print-pdf-files-from-folder-in-powerbuilder-application#reply-27375

Happiness Always
BKR Sivaprakash

You can still use the IE browser control. You have to have Adobe installed in order to view a PDF. My code example has a function of_execwb_print that can be used to print.

https://www.topwizprogramming.com/freecode_webbrowser.html

Hi Tracy;

  Not currently - only in the Web Browser control which has a PrintAsPDF() method. However neither the DW Control or the DataStore control has this method support currently. This would require an enhancement to the DS/DC Native PDF feature.

  However, you can do this with external tool;s (ie: Ayumini) but, these would require an extra purchase & programming.

Regards .. Chris