This concerto survives in only a single manuscript copy, held at Melk Abbey under the shelfmark IV 340. The copy does not name Rosetti as the composer; curiously, Mozart was added as the composer at a later date. Judging by its compositional content, however, it is quickly apparent that this cannot be a work by Mozart, whereas the similarities to Rosetti's horn compositions are striking. Sterling E. Murray therefore lists the concerto among Rosetti's compositions in his catalogue of works. Given the state of the sources, however, a definitive attribution is not possible.
Concerto in E-flat major for Horn, RWV C 43 – audio sample: