Got it! Kschuler, you pointed me in the right direction!
Here is a quick sloppy sample I created, when the Button is clicked, the Rich Text Box is adjusted to fill the entire box.
Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As IntPtr, ByVal nIndex As Integer) As Integer
Public Declare Function GetSystemMetrics Lib "user32.dll" (ByVal nIndex As Integer) As Integer
Public Const GWL_STYLE As Integer = (-16)
Public Const WS_VSCROLL As Integer = &H200000
Public Const WS_HSCROLL As Integer = &H100000
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
RichTextBox1.SelectAll()
RichTextBox1.SelectionAlignment = HorizontalAlignment.Center
Dim bVScrollBar As Boolean
bVScrollBar = ((GetWindowLong(Me.RichTextBox1.Handle, GWL_STYLE) And WS_VSCROLL) = WS_VSCROLL)
Select Case bVScrollBar
Case True
Do
RichTextBox1.ZoomFactor = RichTextBox1.ZoomFactor - 0.01
bVScrollBar = ((GetWindowLong(Me.RichTextBox1.Handle, GWL_STYLE) And WS_VSCROLL) = WS_VSCROLL)
If bVScrollBar = False Then Exit Do
Loop
Case False
Do
RichTextBox1.ZoomFactor = RichTextBox1.ZoomFactor + 0.01
bVScrollBar = ((GetWindowLong(Me.RichTextBox1.Handle, GWL_STYLE) And WS_VSCROLL) = WS_VSCROLL)
If bVScrollBar = True Then
Do
RichTextBox1.ZoomFactor = RichTextBox1.ZoomFactor - 0.01
bVScrollBar = ((GetWindowLong(Me.RichTextBox1.Handle, GWL_STYLE) And WS_VSCROLL) = WS_VSCROLL)
If bVScrollBar = False Then Exit Do
Loop
Exit Do
End If
Loop
End Select
End Sub