The Keywords property associates keywords with a PDF file.
Examples:
The following VBA example publishes the active document to PDF and specifies the file's author, subject, and keywords.
Sub Test()
With ActiveDocument.PDFSettings
.Author = "Graphix Design, Inc"
.Keywords = "Animals, Farm, Bulls"
.Subject = "Animal Farms"
End With
ActiveDocument.PublishToPDF "C:\MyFarm.pdf"
End Sub