According to information in the file in the Stichting Iconografisch Bureau, the sitter was first identified by Jonkvrouwe Clara H. de Jonge in 1936. Frederik was son of Willem van Zuylen van Nyevelt and Agnes Boot. He was Lord of Bergambacht, 's Heeraartsbergen Achterbroek and Crayestein, and married Anna Wtenengh in 1597. He later became Governor of Gorinchem and Woudrichem, and represented the States of Utrecht at the Synod of Dordrecht in 1618.
If the inscription and date on the reverse are accepted as authentic, it would indicate that the portrait was posthumus, perhaps based on an earlier example

See illustration