Words that have identical vowel-based rhyme sounds in the tonic syllable. Moreover, that tonic syllable must start with a different consonantal sound.
There are no pure rhymes for "r and f".
Words that have a pure rhyme on their last syllable only.
chef
    clef
      deaf
        f
          greff
            ref
              Geoff
                Jeff
                  Leff
                    Neff
                      Sheff
                        Steph
                          MILF
                            Hef
                              Brezhnev
                                UNICEF
                                  Words that "almost" rhyme on the vowel-based rhyme sound of the stressed syllable like: be/eat or maybe/shapely.
                                  There are no near rhymes for "r and f".
                                  Rhymes made up of more than one word. For instance, "jealous" and "tell us" or "shaky" and "make me."
                                  There are no mosaic rhymes for "r and f".