I'm trying to put signature form fields in a given position at specific pages using iText for .NET (v7.0.4). The code I'm working on is the following:

```
public static void test()
    {
        using (PdfDocument pdfDoc = new PdfDocument(new PdfWriter(@"c:\temp\pippo.pdf")))
        {
            //Add some blank pages
            pdfDoc.AddNewPage();
            pdfDoc.AddNewPage();
            pdfDoc.AddNewPage();

            //Instantiate a Signature Form Field using factory
            PdfSignatureFormField sgnField = 
                PdfFormField.CreateSignature(pdfDoc, new Rectangle(100, 100, 200, 100));

            //setting name and page
            sgnField.SetFieldName("pluto");
            sgnField.SetPage(1);

            //Adding to AcroForm
            PdfAcroForm.GetAcroForm(pdfDoc, true).AddField(sgnField);
        }
    }

```

The output document (pippo.pdf) has the signature field in first page and that's the expected behavior. The issue is that I can see the signature field even in the last page (the third page, in this case).

Moreover, if I remove the last page, by calling `pdfDoc.RemovePage(3);`, the signature field disappear even from the first page. 

The question is: how to make signature form fields not replicated in the last page? Any suggestion is really well accepted!