His approach is defined by a mastery of drypoint and etching, techniques he used to translate the textures of oil painting into print. Geddes often produced copies of works by Anthony van Dyck and Peter Paul Rubens, such as his portrait of Nikolaas Rockox. These were not mere reproductions. He used varied line weights and tonal contrasts to capture the character of the original subjects. His original compositions, like Kind met appel or Oude vrouw bekijkt een ring, show a preference for domestic, quiet moments over grand historical narratives.

Modern collectors value Geddes for his ability to balance classical portraiture with a more experimental, graphic sensibility. His etchings possess a sketch-like quality that feels immediate and less formal than the finished oils of his contemporaries. The small scale and detailed execution of his prints make them suitable for contemporary interiors. They offer a connection to the traditions of the Old Masters through a nineteenth-century lens.