Hi David;
I don't know whether the recipe you are looking for is the one several people have already posted using a cake mix or if you want a scratch recipe. I found one, so here it is. Hope this helps.
This makes a "tube pan" cake that is moist and delicious. It's the butter/rum glaze/syrup that soaks in after baking that makes it fabulous!

Ingredients:
1 cup butter
2 cups white sugar
4 eggs
1 cup buttermilk
1 teaspoon vanilla extract
3 cups all-purpose flour
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1 pinch salt
1 teaspoon rum extract
1 cup butter
1 cup white sugar
1/2 cup rum


Directions:
1 Preheat oven to 350 degrees F (175 degrees C). Grease and flour one 9 or 10 inch tube pan.
2 Cream 1 cup of the butter and 2 cups of the white sugar together. Add eggs one at a time mixing well after each one.
3 Sift the flour, baking powder, baking soda, and salt together and add alternately with the buttermilk to the egg mixture. Stir in the vanilla and rum extracts. Pour batter into prepared pan.
4 Bake at 350 degrees F (175 degrees C) for 1 hour. Remove cake from oven and pour all of the Rum Butter glaze over cake while still warm. Leave cake in pan for 2 hours before removing to serving dish.
5 To Make Butter Rum Glaze: Melt the remaining 1 cup of the butter and 1 cup of white sugar over low heat. Remove from heat and stir in rum. Use immediately to glaze cake.
Makes 1 - 9 or 10 inch tube pan