Results from ferromagnetic resonance experiments made on epitaxially grown Fe/KNiF3 bilayers are presented. The bilayers exhibit exchange bias and coercivity previously studied using low-temperature magnetometry. In this paper, results from ferromagnetic resonance (FMR) experiments on the FeKNiF3 bilayers are reported. A rotatable anisotropy is identified, and temperature dependence of all anisotropy fields are examined. A possible correlation between the bias field and the rotatable anisotropy is proposed. Linewidths are also studied and possible correlations between coercive fields and FMR linewidths are discussed. A model for the rotatable anisotropy is proposed which ascribes the existence of exchange bias to small uncompensated regions at the interface and rotatable anisotropy to exchange coupling combined with long-range disorder within the antiferromagnet. A possible realization of this mechanism through exchange-coupled grains is discussed in relation to other models for exchange bias in disordered structures.