first　ｔｙpe　"te" then type "xi" or"li"

They use 'ティ’(te + 'small' i) for the 'ti' sound such as : ティー (tea)　パ－ティ― (party) , ティ－シャツ (T shirt). it sounds like 'ti:' , different than 'てい(テイ)' which sounds 'te i' as itself. it might be only used for writing the foreign words in 'カタカナ’, as i guess there is no native word which has 'てぃ(ティ)' 'ti' sound in Japanese.

Hello, Cade, it's Noriko. Thank you for counting me in. As Young told you, Japanese originally doesn't have ‘ティ’　sound. That's why you find ‘ティ’　sound only in Katakana, which is used to write imported words from foreign countries. And F7 key allows you to change ひらがな to カタカナ; it's an additional information just in case this were new informatin to you.