The Schiff small‐angle approximation for plane‐wave scattering by a dielectric is integrated over an appropriate angular distribution of incident plane waves in order to represent finite‐beam scattering. The intensity distribution near the forward direction where incident and scattered waves interfere can now be expressed in a meaningful way. If the radius of the incident beam is not large relative to the dimensions of the scattering system, the scattered wave is seriously modified. A simple definition of cross section is chosen, and an extended optical theorem for total cross sections is derived.