North America dwarfs South Africa: about 24,710,000 km² km² against 1,221,609 km² km². At true size North America is about 20.2× larger — the whole of South Africa fits into North America roughly 20 times.
The old Mercator map treated both about equally (1× vs 1.3× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
South Africa fits 20× into North America.