Changer la taille du texte quand on imprime une textbox

Imports System.IO

Public Class printco
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then

            Dim SR As New StreamReader(OpenFileDialog1.FileName)
            TextBox1.Text = SR.ReadToEnd
            SR.Close()
        End If
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        PrintDocument1.PrinterSettings.Copies = 1
        PrintDocument1.Print()
    End Sub

    Private Sub PrintDocument1_PrintPage(sender As Object, e As Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage
        e.Graphics.DrawString(TextBox1.Text, Font, Brushes.Black, 100, 100)
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class