Her article in thepeerage is here.
According to artuk.org, this portrait is in the possession of the Perth and Kinross Council that has six venues.
From artuk.org.
Lady Seton Steuart wears a low-cut dress with a high waistline for her Raeburn portrait from about 1812.
Keywords: 1812, Raeburn, Elizabeth Margaret Steuart, Elizabeth Margaret Seton-Steuart, Steuart family, Seton-Steuart family, British, curly coiffure, coat, lapels, lining, long sleeves, Empire bodice, vee décolletage, neckline ruff, waist band, Empire low waistline, close skirt, wrap