The attribution is based on comparison with the portrait of Tietske van Botnia, signed and dated 1610, at Harinxma State, Beesterszwaag (see A. Wassenbergh, De Portretkunst in Friesland in de Zeventiende Eeuw, 1967, p. 86, fig. 30)

Dr Lyckle de Vries has kindly confirmed the attribution on the basis of a photograph