Tony,
What Hog says about substituting butter for oil in a dough recipe is correct. Since a teaspoon of butter weighs about the same as a teaspoon of oil (it's actually a little bit more but not in a significant sense), you can substitute butter for the oil on an equal basis. That is, the baker's percents can be the same. For a dough that does not contain any oil, Tom Lehmann frequently suggests adding 3% butter to get the benefits of the butter flavor.
Peter