If you are trying to support multiple users who have a variety of Word versions, you cannot just give them RTF files; Microsoft made sure of that. Instead, you must provide documents in .doc or .docx format.
To produce Word files in .doc or .docx format from RTF files generated by DITA2Go:
Or, you can create a Word VBA macro that will do all that for you; for example, a Word macro like the following macro for .doc output:
Sub LoadRtfFile()
'
' LoadRtf2007 Macro
' Macro recorded 5/31/2010 by Omni Systems
'
Dim nameStr As String
Selection.WholeStory
Selection.Fields.Update
nameStr = Replace(ActiveDocument.FullName, ".rtf", ".doc")
ActiveDocument.SaveAs FileFormat:=wdFormatDocument, _
FileName:=nameStr, LockComments:=False
Selection.StartOf
End Sub
See the Word VBA reference for details. Word files in .doc or .docx format can be distributed to users who have any version of Word.