Sending email with outlook signature

hi all

Function GetBoiler(ByVal sFile As String) As String
'**** Kusleika
    Dim fso As Object
    Dim ts As Object
    Set fso = CreateObject("Scripting.FileSystemObject")
    Set ts = fso.GetFile(sFile).OpenAsTextStream(1, -2)
    GetBoiler = ts.readall
    ts.Close
End Function

Sub Mail_Outlook_With_Signature_Plain()
' Don't forget to copy the function GetBoiler in the module.
' Working in Office 2000-2007
    Dim OutApp As Object
    Dim OutMail As Object
    Dim strbody As String
    Dim SigString As String
    Dim Signature As String
 
    Set OutApp = CreateObject("Outlook.Application")
    OutApp.Session.Logon
    Set OutMail = OutApp.CreateItem(0)
 
    strbody = "Hi there" & vbNewLine & vbNewLine & _
              "This is line 1" & vbNewLine & _
              "This is line 2" & vbNewLine & _
              "This is line 3" & vbNewLine & _
              "This is line 4"
 
    SigString = "C:\Documents and Settings\" & Environ("username") & _
                "\Application Data\Microsoft\Signatures\Mysig.txt"
 
    If Dir(SigString) <> "" Then
        Signature = GetBoiler(SigString)
    Else
        Signature = ""
    End If
 
    On Error Resume Next
    With OutMail
        .To = "ron@debruin.nl"
        .CC = ""
        .BCC = ""
        .Subject = "This is the Subject line"
        .Body = strbody & vbNewLine & vbNewLine & Signature
        'You can add files also like this
        '.Attachments.Add ("C:\test.txt")
        .Send   'or use .Display
    End With
    On Error GoTo 0
 
    Set OutMail = Nothing
    Set OutApp = Nothing
End Sub

This macro sends an email with a body and signature, but this works only if you manually provide the user signature file which is MySig.txt in this macro. My problem is that this same macro would be used by different users. So it should dynamically read the signature file from user's location C:\Documents and Settings\" & Environ("username") "\Application Data\Microsoft\Signatures\[user file]" and send email with that particular user's signature.

Please guide me as how this could be achieved.