function GetRTFText(ARichEdit: TRichedit): string;
 var
  ss: TStringStream;
  emptystr: string;
 begin
  emptystr := '';
  ss := TStringStream.Create(emptystr);
  try
  ARichEdit.PlainText := False;
  ARichEdit.Lines.SaveToStream(ss);
  Result := ss.DataString;
  finally
  ss.Free
  end;
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 begin
  Memo1.Text := GetRTFText(RichEdit1);
 end;