We analyze the proposed Karlsruhe electron storage ring for X-ray in-depth lithography using the 3rd order charged particle beam transport code MARYLIE 3.0. The ring features four 90° superconducting bending magnets. A numerical calculation of their field provides the longitudinal dependence of the multipole expansion coefficients. These are used by the code SCB to compute the Lie algebraic transfer map. Subsequent particle tracking with MARYLIE is employed to find dynamic apertures. Two different magnet designs which both lead to satisfactory dynamic apertures are presented.