Attached files are displayed on "Attachments" tab when you view PDF document in Adobe Reader:

' this example demonstrates how to attach file to generated PDF document using PDFDoc Scout

Set PDFDoc = CreateObject("PDFDocScout.PDFDocument") ' create PDFDoc object
PDFDoc.InitLibrary "demo", "demo" ' initialize library

PDFDoc.OutputFileName = "AttachedFiles.pdf" ' set output filename for PDF document
PDFDoc.AutoOpenGeneratedPDF = true ' automatically open generated PDF document in default PDF viewer application

PDFDoc.BeginDocument ' starts PDF document generation

' add text to a page
PDFDoc.Page.AddText "Testing Attached Files ('sample.png' file attached - see ATTACHMENTS tabs at the left)", 100, 10, 0

PDFDoc.AddAttachedFile "sample.png", "Sample.png File"

PDFDoc.EndDocument ' close pdf document generation

' disconnect from library
Set PDFDoc = Nothing