The title refers to this as having a rye sourdough. Actually, this starter is prepared from a standard sourdough culture, not a rye culture. And, as a possible alternative mentioned by Hamelman, I used rye chops rather than the cracked rye called for by the recipe. Apart for that, I prepared the loaf as described in the book.
The results were excellent. This produced a lovely loaf that is now one of my favorites.