Impresion: Propiedad PaperSize de PageSettings

[geralive]

Código:

Dim pageset As New Printing.PageSettings
        Dim ppsz As Printing.PaperSize

        For Each ppsz In pageset.PrinterSettings.PaperSizes
            If ppsz.Kind = Printing.PaperKind.Letter Then
                pageset.PaperSize = ppsz
            End If
        Next

        PrintDocument1.DefaultPageSettings = pageset

ya encontre la respuesta a mi pregunta