RIF (Rule Interchange Format) has become W3C's candidate recommendation on rule interchange. To let RIF represent and interchange fuzzy knowledge in the Semantic Web, we propose RIF-FRD (RIF Fuzzy Rule Dialect), a rule interchange format based on fuzzy sets, defining its XML syntax and metamodel. Based on the metamodel, we propose a fuzzy RIF framework—f-RIA (fuzzy Rule Interchange Architecture), which supports rule interchange between RIF-FRD and some important fuzzy rule languages.