I am using the following class.
RichTextBoxPrint.vb

Option Explicit On

Imports System
Imports System.Windows.Forms
Imports System.Drawing
Imports System.Runtime.InteropServices
Imports System.Drawing.Printing

Public Class RichTextBoxPrint
Inherits RichTextBox
' Convert the unit that is used by the .NET framework (1/100 inch)
' and the unit that is used by Win32 API calls (twips 1/1440 inch)
Private Const AnInch As Double = 14.4

<StructLayout(LayoutKind.Sequential)> _
Private Structure RECT
Public Left As Integer
Public Top As Integer
Public Right As Integer
Public Bottom As Integer
End Structure

<StructLayout(LayoutKind.Sequential)> _
Private Structure CHARRANGE
Public cpMin As Integer ' First character of range (0 for start of doc)
Public cpMax As Integer ' Last character of range (-1 for end of doc)
End Structure

<StructLayout(LayoutKind.Sequential)> _
Private Structure FORMATRANGE
Public hdc As IntPtr ' Actual DC to draw on
Public hdcTarget As IntPtr ' Target DC for determining text formatting
Public rc As RECT ' Region of the DC to draw to (in twips)
Public rcPage As RECT ' Region of the whole DC (page size) (in twips)
Public chrg As CHARRANGE ' Range of text to draw (see above declaration)
End Structure

Private Const WM_USER As Integer = &H400
Private Const EM_FORMATRANGE As Integer = WM_USER + 57

Private Declare Function SendMessage Lib "USER32" Alias "SendMessageA" (ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wp As IntPtr, ByVal lp As IntPtr) As IntPtr

' Render the contents of the RichTextBox for printing
' Return the last character printed + 1 (printing start from this point for next page)
Public Shared Function Print(ByVal charFrom As Integer, ByVal charTo As Integer, ByVal e As PrintPageEventArgs) As Integer

' Mark starting and ending character
Dim cRange As CHARRANGE
cRange.cpMin = charFrom
cRange.cpMax = charTo

' Calculate the area to render and print
Dim rectToPrint As RECT
rectToPrint.Top = e.MarginBounds.Top * AnInch
rectToPrint.Bottom = e.MarginBounds.Bottom * AnInch
rectToPrint.Left = e.MarginBounds.Left * AnInch
rectToPrint.Right = e.MarginBounds.Right * AnInch

' Calculate the size of the page
Dim rectPage As RECT
rectPage.Top = e.PageBounds.Top * AnInch
rectPage.Bottom = e.PageBounds.Bottom * AnInch
rectPage.Left = e.PageBounds.Left * AnInch
rectPage.Right = e.PageBounds.Right * AnInch

Dim hdc As IntPtr = e.Graphics.GetHdc()

Dim fmtRange As FORMATRANGE
fmtRange.chrg = cRange ' Indicate character from to character to
fmtRange.hdc = hdc ' Use the same DC for measuring and rendering
fmtRange.hdcTarget = hdc ' Point at printer hDC
fmtRange.rc = rectToPrint ' Indicate the area on page to print
fmtRange.rcPage = rectPage ' Indicate whole size of page

Dim res As IntPtr = IntPtr.Zero

Dim wparam As IntPtr = IntPtr.Zero
wparam = New IntPtr(1)

' Move the pointer to the FORMATRANGE structure in memory
Dim lparam As IntPtr = IntPtr.Zero
lparam = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange))
Marshal.StructureToPtr(fmtRange, lparam, False)

' Send the rendered data for printing
res = SendMessage(Handle, EM_FORMATRANGE, wparam, lparam)

' Free the block of memory allocated
Marshal.FreeCoTaskMem(lparam)

' Release the device context handle obtained by a previous call
e.Graphics.ReleaseHdc(hdc)

' Return last + 1 character printer
Return res.ToInt32()
End Function

End Class

I need to be able to use this in a form

How do I go about declaring this?

I have a form called frmComments where I need to use this. How do I go about declaring this?

Me.txtComments = New RichTextBoxPrint ? This ok?

'
'txtComments
'
Me.txtComments.Location = New System.Drawing.Point(16, 64)
Me.txtComments.Name = "txtComments"
Me.txtComments.Size = New System.Drawing.Size(672, 344)
Me.txtComments.TabIndex = 7
Me.txtComments.Text = ""
This will be the size of the RichTextBox

Now so far I have the following error:
C:\Documents and Settings\mcupryk.MCUPRYK-1\My Documents\Visual Studio Projects\ZLAPS\LR_EXP\frmComments.vb(212): The variable 'txtComments' is either undeclared or was never assigned.



' Send the rendered data for printing
res = SendMessage(Handle, EM_FORMATRANGE, wparam, lparam)

C:\Documents and Settings\mcupryk.MCUPRYK-1\My Documents\Visual Studio Projects\ZLAPS\LR_EXP\RichTextBoxPrint.vb(86):
Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class.