// Install IronPdf with Nuget:  PM> Install-Package IronPdf
using IronPdf;

// create a new PDF or edit an existing document.
PdfDocument Pdf = PdfDocument.FromFile("existing.pdf");

// Create a PDF annotation object
var Annotation = new IronPdf.PdfDocument.TextAnnotation()
    {
        Title = "This is the major title",
        Subject = "This is a subtitle",
        Contents = "This is the long 'sticky note' comment content...",
        Icon = PdfDocument.TextAnnotation.AnnotationIcon.Help,
        Opacity = 0.9,
        Printable = false,
        Hidden = false,
        OpenByDefault = true,
        ReadOnly = false,
        Rotateable = true
    };

// Add the annotation "sticky note" to a specific page and location within any new or existing PDF.
Pdf.AddTextAnnotation(Annotation, 1, 150, 250);


Pdf.SaveAs("existing.pdf");

' Install IronPdf with Nuget:  PM> Install-Package IronPdf
Imports IronPdf

' create a new PDF or edit an existing document.
Private Pdf As PdfDocument = PdfDocument.FromFile("existing.pdf")

' Create a PDF annotation object
Private Annotation = New IronPdf.PdfDocument.TextAnnotation() With {
	.Title = "This is the major title",
	.Subject = "This is a subtitle",
	.Contents = "This is the long 'sticky note' comment content...",
	.Icon = PdfDocument.TextAnnotation.AnnotationIcon.Help,
	.Opacity = 0.9,
	.Printable = False,
	.Hidden = False,
	.OpenByDefault = True,
	.ReadOnly = False,
	.Rotateable = True
}

' Add the annotation "sticky note" to a specific page and location within any new or existing PDF.
Pdf.AddTextAnnotation(Annotation, 1, 150, 250)


Pdf.SaveAs("existing.pdf")