Well guys, I have seen this asked before. About how to make text SubScript. As like H2O would be H²O (lower 2). I just wrote this for all yous that want it.
Treat it with care .
It's not the best.
But this gives you the idea.


Code:
Private Sub SubScript(rtb As RichTextBox, SubString As String, Size As Integer)

    SubString$ = Mid$(Trim$(rtb.Text), InStr(rtb.Text, SubString$), Len(SubString$))
    With rtb
        .SelStart = InStr(1, rtb.Text, SubString$) - 1
        .SelLength = Len(SubString$)
        .SelFontSize = Size
        .SelText = SubString$
    End With
    
End Sub


Usage

Private Sub Command1_Click()
    Call SubScript(RichTextBox1, "MyString", 8)
End Sub