what is the design procedure for designing SIW caviy

You can design rectangular cavity the same way as traditional waveguide. Air filled waveguide and dielectric filled waveguide. With small height. I would start from making test-siw design to find waveguide width which produces symmetrical EM field on both axis in plane of waveguide. Just simulate SIW of few wavelengths, arbitrary length. Then, when wavelength in waveguide is known, I will make rectangle of half wavelength surrounded by vias on all four sides. Then I do inset feeding of rectangular SIW and try to optimize. You can start by any SIW band pass filter. Any half wave part between "iris" vias is a cavity. Also there are cylindrical SIW resonators, but I am unsure about them. The one with two insets that can be googled somehow have whole wavelength inside (some modes?). So I suggest to take part of band pass SIW, prolong iris vias, and add inset feeding. Not traditional siw to microstrip transition!