The title Rosoman/Rosoman's features several times in the book mentioned below - now out-of-print, but an invaluable item for researcher's seeking Islington history. It is an A-Z anthology of streetname titles.
However as for the title shown in your document, as reported in a fine publication "Streets with a story; Islington", Eric Willats [Principal Librarian at Islington] pub 1986 by I.L.E.T (a council body) -
'Rosoman's Buildings c.1770. By 1878 were nos 19-24 Islington Green.
I can recommend an excellent publication from
https://alangodfreymaps.co.uk/ who reprinted OS map
1871 Clerkenwell/The Angel Sheet No 50 which clearly shows Islington Green (off centre top R). They post RM 24 often same day.
Your enquiry mentions no date to accompany the document which might aid any future search of census records.