The name rhymes with "frighten".

Source: https://dictionary.cambridge.org/pronunciation/english/crich...

Also a Source: Name is Scottish origin, I live in Scotland.

Also a source: back in the '90s, I once resolved a disagreement with a friend over the pronunciation of the man's name by emailing him to ask, and "Crichton rhymes with 'frighten'" was his exact answer.

I mixed up German and English pronunciation of "ei". The German one sounds like English "i", so it would be Crighton.