  Single photoionization cross sections for Kr-like Rb$^+$ ions are reported in
the energy (wavelength) range 22 eV (564 \AA) to 46 eV (270 \AA). Theoretical
cross section calculations for this {\it trans}-Fe element are compared with
measurements from the ASTRID radiation facility in Aarhus, Denmark and the dual
laser plasma (DLP) technique, at respectively 40 meV and 35 meV FWHM energy
resolution. In the photon energy region 22 - 32 eV the spectrum is dominated by
excitation autoionizing resonance states. Above 32 eV the cross section exhibit
classic Fano window resonances features, which are analysed and discussed.
Large-scale theoretical photoionization cross-section calculations, performed
using a Dirac Coulomb $R$-matrix approximation are bench marked against these
high resolution experimental results. Comparison of the theoretical work with
the experimental studies allowed the identification of resonance features and
their parameters in the spectra in addition to contributions from excited
metastable states of the Rb$^+$ ions.
