go to adobes website and download adobe PS.
its a print driver and can generate pdf's. you'll install it in the os9 system extensions folder. after its installed start up in osx and and go to the preferences panel and click on the **Classic preference icon. under the advanced tab (in 10.2.4) you will see a drop down menu. select Open Extensions Manager. then start classic. this will open the extension manager during start up. go through the extensions and check the box for the Adobe PS driver. also you will need to go to the chooser once in classic (if you can, im not sure the chooser is available in classic mode) and select the Adobe PS driver in the chooser. now try to make the pdf.
BUT FIRST 😀 you most likely have the Adobe PS driver OR LaserWriter 8 (another driver that can generate pdfs) in your os9 extensions folder already....SOOOooo, go to preferences in osx and follow the steps above about how to set up the **Classic preferences.
hope i didnt confuse you.