"Retherford" is a fairly uncommon surname, and its spelling can be a bit tricky to decipher. When looking at the IPA transcription, we see that the "th" sound is spelled with the letter combination "th," rather than as a single letter. The first syllable, "reth," is spelled as expected. The second syllable, "erford," includes a schwa sound indicated by the upside-down "e," and spells the "ford" sound as a single word. Overall, "Retherford" is spelled phonetically as /ˈɹɛθəɹfərd/.