I've found an assortment of flours work without needing to tweak the ratios of starter or oil. Spelt is my favorite to use, but I've also used all-purpose white, whole wheat pastry flour, and rye flour.
Preheat your oven to 350ºC (180ºC). Line a sheet pan with a silicon liner.
Combine the starter, flour, oil, salt, seeds, and spices, if using in a small bowl. Stir with a wooden spoon until well mixed.
Scrape dough onto the silicon liner. Dust top with flour, and roll exceptionally thin (preferably 1/16-inch thick), dusting with more flour as needed since the dough is quite sticky. Prick the dough quickly and gently with the tines of fork (this helps stop them from puffing up). Use a pizza wheel or pastry cutter to "score" the crackers (see photo in post).
Bake 16 to 18 minutes, depending on thickness, until crackers are golden and crisp. Let cool a few minutes before breaking up. Store cooled crackers in a tightly sealed glass jar.