' Override File -> Save
Public Sub FileSave()

    ActiveDocument.Save
    SaveActiveDocumentAsPdf

End Sub

' Override File -> Save As...
Public Sub FileSaveAs()

    ActiveDocument.SaveAs
    SaveActiveDocumentAsPdf

End Sub

Sub SaveActiveDocumentAsPdf()

    On Error GoTo Errhandler

    If InStrRev(ActiveDocument.FullName, ".") <> 0 Then

        Dim strPath As String
        strPath = Left(ActiveDocument.FullName, InStrRev(ActiveDocument.FullName, ".") - 1) & ".pdf"

        ActiveDocument.SaveAs2 FileName:=strPath, FileFormat:=wdFormatPDF
    End If

    On Error GoTo 0

    Exit Sub

Errhandler:

    MsgBox "There was an error saving a copy of this document as PDF. " & _
    "Ensure that the PDF is not open for viewing and that the destination path is writable. Error code: " & Err

End Sub