Bring a large pot of salted water to a boil. Add potatoes and cook until tender but still firm, about 15 minutes. Drain, cool, peel and slice.
Place eggs in a saucepan and cover with cold water. Bring water to a boil and immediately remove from heat. Cover and let eggs stand in hot water for 10 to 12 minutes. Remove from hot water, cool, peel and slice.
In a 9×13 inch casserole dish layer potatoes and eggs, sprinkling each layer of eggs with seasoning salt, ending with potatoes.
In a small saucepan over low heat, melt margarine with sour cream. Pour over potatoes and sprinkle lightly with seasoning salt.