  In this paper, a Roos like bound on the minimum distance for skew cyclic
codes over a general field is provided. The result holds in the Hamming metric
and in the rank metric. The proofs involve arithmetic properties of skew
polynomials and an analysis of the rank of parity-check matrices. For the rank
metric case, a way to arithmetically construct codes with a prescribed minimum
rank distance, using the skew Roos bound, is also given. Moreover, some
examples of MDS codes and MRD codes over finite fields are built, using the
skew Roos bound.
