Place yeast, flour, salt sugar and rosemary in mixer with bread hook attachment. Make sure that salt is separated by flour. Start mixer on 1st speed to combine dry ingredients. Then, gradually add water, and then add olive oil. Stop mixer to check dough. All the flour should be incorporated. Mix more if necessary. Allow dough to rise again until it has doubled in size (about 30 to 40 minutes). Punch down dough with your hands. Roll dough out with a rolling pin so that it fits the size of the sheet pan, and is about 3/4 inch thick. Lightly oil top of dough with olive oil. Let dough rise again for about 20 minutes. Preheat oven to 425 degrees. Press dimples into dough with fingers and sprinkle with kosher salt. Bake until done (about 20 to 30 minutes or golden brown).