The word "Smeath" is not a common word in English, and its spelling is not straightforward. It is pronounced as /smiθ/ with the "th" sound as in "thin." The "S" in the beginning is pronounced as /s/ sound. The word does not follow any clear pronunciation or spelling rules. The best way to spell and pronounce it accurately is by looking at the context it is used in and comparing it to other similar-sounding words.