  The angle-dependences of the magnetoresistance of two different isotopic
substitutions (deuterated and undeuterated) of the layered organic
superconductor \kappa-(ET)2Cu(NCS)2 are presented. The angle dependent
magnetoresistance oscillations (AMRO) arising from the quasi-one-dimensional
(Q1D) and quasi-two-dimensional (Q2D) Fermi surfaces in this material are often
confused. By using the Boltzman transport equation extensive simulations of the
AMRO are made that reveal the subtle differences between the different species
of oscillation. No significant differences are observed in the electronic
parameters derived from quantum oscillations and AMRO for the two isotopic
substitutions. The interlayer transfer integrals are determined for both
isotopic substitutions and a slight difference is observed which may account
for the negative isotope effect previously reported [1]. The success of the
semi-classical simulations suggests that non-Fermi liquid effects are not
required to explain the interlayer-transport in this system.
