This funnel is conjectural. Dutch & German Coaster Fleets describes yellow with the house flag, lettered RSSL and varying slightly between ships. It might mean a panel or a flying-flag emblem; Mitchell does not make clear whether his flag drawing was also intended as a funnel design.
Schepers Rhein-See Linie of Dusiburg appears in registers from 1956–57 and later as Heinrich Schepers Rhein-Se-Linie. Mitchell records cessation in the late 1980s.
Keep the explicit scope label independent; no alias or company identity is inferred.