I know that he Riemann Stieltjes integral is a generalization of the Riemann integral, i.e. we integrate one function say $f$ with respect to another say $g$ and then we write $\int f(x)d(g(x))$.
But I'd like to see it geometrically, or at least to try.
Because I can see the geometric of the Riemann integral which is the area under the function $f$, but how is for the Stieltjes-integral??