The Kosterlitz–Thouless transition of 4He films adsorbed in packed powders is studied using a third-sound technique. We have extended the powder-grain diameter to a larger size (50 μm Al2O3) and to a smaller size (150 Å Carbolac II) than in our previous work. The results show that finite-size effects are very pronounced in the Kosterlitz–Thouless transition and can be observed even up to micrometre-length scales.