It's Land O' Lakes, if that matters. No butter haters, please.... ;-)
On average in the US there is about 1/4 tsp of salt in a stick of butter. So about an 1/8 of a tsp should be about right.
I like a little more salt in my baking, I'd up it to a 1/4 tsp of fine salt in a loaf of banana bread. That's the normal amount I add to all my pastry and quick breads.