Я нашел этот фрагмент кода при исследовании iTextSharp для себя и нашел 2 человек, ссылающихся на Open Actions. Я включил фрагмент из http://www.developerbarn.com/blogs/richyrich-33.htm ниже:
PdfWriter writer = PdfWriter.GetInstance(doc, HttpContext.Current.Response.OutputStream);
//this creates a new destination to send the action to when the document is opened. The zoom in this instance is set to 0.75f (75%). Again I use doc.PageSize.Height to set the y coordinate to the top of the page. PdfDestination.XYZ is a specific PdfDestination Type that allows us to set the location and zoom.
PdfDestination pdfDest = new PdfDestination(PdfDestination.XYZ, 0, doc.PageSize.Height, 0.75f);
//open our document
doc.Open();
//here you put all the information you want to write to your PDF
//create a new action to send the document to our new destination.
PdfAction action = PdfAction.GotoLocalPage(1, pdfDest, writer);
//set the open action for our writer object
writer.SetOpenAction(action);
//finally, close our document
doc.Close();