The key detail from the other link is this:
Set Variable [$FilePath ; "filemac:" & Get ( TemporaryPath ) & $ActiveName & "Report.pdf"]
modifying it to fit your described set up and to make the basic syntax cross platform:
Set Variaable [$FilePath; "File:" & "Path to enclosing folder in quotes/" & YourTable::YourFolderNameField & "/" & YourTable::YourFileNameField & ".PDF"]
"path to enclosing folder" will differ with your platform, but will represent that part of the filepath that is the same for all your possible PDF folder locations. If these are different folders on your desktop, you can use Get (DesktopPath) for this part. The part where you specify a folder and file name can be a single field with both items entered, separated by a / or you can enter this data in separate fields. I suggest separate fields with the folder name selected from a value list of folder names as this name must be the name of a folder that already exists.
yep, brilliant, this is the way i will go
can i hire you to do this for me? I am not a FM programmer. I just need to create certificates in PDF and email it to the winners of our competition.