In this work, we propose an equivalent circuit that predicts the reflectance spectra of a resonant metasurface with a pronounced variation in the resonant frequency versus the incidence angle. Two different unit-cell geometries of such a metasurface are compared, and the possibility of using both for sensing of submicron-thick films (analytes) is studied. In contrast to conventional metasurface sensors that rely on a spectral resonance shift, the angle-selective metasurface can be employed for sensing using a single-frequency THz source. The proposed circuit quantitatively predicts the reflectance spectra at different incidence angles and allows one to calculate the required angle of mechanical rotation of the metasurface that compensates for the resonance shift when a submicron analyte is deposited.