The word "most letting" is spelled with the phonetic transcription /məʊst ˈlɛtɪŋ/. In this transcription, the vowel sound in "most" is pronounced as "əʊ", which is a diphthong that combines the sounds of "o" and "u". The consonant sound in "letting" is spelled with the letter "t", but is pronounced as a voiceless "t" sound due to the final "ing" ending. Overall, the spelling of "most letting" accurately reflects its pronunciation using English phonetics.