VB.NET PDF Viewer, Reader Library
How to open, display, add, delete, Adobe PDF file attachment using VB.NET in .net web, windows, wpf application

Dim inputFilePath As String = Program.RootPath + "\\" + "2.pdf"
Dim outputFilePath As String = Program.RootPath + "\\" + "Annot_7.pdf"

' open a PDF file
Dim doc As PDFDocument = New PDFDocument(inputFilePath)
' get the 1st page
Dim page As PDFPage = doc.GetPage(0)

' create the annotation
Dim annot As PDFAnnotFileAttach = New PDFAnnotFileAttach()

annot.Position = New PointF(100.0F, 100.0F)
annot.FilePath = "C:\AttachmentFile.txt"

' add annotation to the page
PDFAnnotHandler.AddAnnotation(page, annot)

' save to a new file
doc.Save(outputFilePath)

Dim inputFilePath As String = Program.RootPath + "\\" + "Annot_7.pdf"

Dim doc As PDFDocument = New PDFDocument(inputFilePath)
Dim annots = PDFAnnotHandler.GetAllAnnotations(doc)
For Each annot As IPDFAnnot In annots
    If TypeOf annot Is PDFAnnotFileAttach Then
        Dim obj As PDFAnnotFileAttach = annot
        Console.WriteLine("Color: " + obj.Color.ToString())
    End If
Next

Dim inputFilePath As String = "C:\1_Annots.pdf"

Dim doc As PDFDocument = New PDFDocument(inputFilePath)
' get all annotations in the 1st page
Dim page As PDFPage = doc.GetPage(0)
Dim annots = PDFAnnotHandler.GetAllAnnotations(page)
' remove all annotations in the 1st page
PDFAnnotHandler.DeleteAnnotation(doc, annots)