You should add ‘-으시/시-’ to verbs/adjectives in which the acting person deserves respect, regardless of who you are speaking to. You can add ‘-시-’ to word stems ending in a vowel and ‘-으시-’ to stems ending in a consonant. Once ‘-으시/시-’ is added, the verb/adjective gets conjugated as usual as if the stem ended in ‘-으시/시-’.
● 아버지께서 텔레비전을 보십니다. (My father watches TV.)
● 할머니께서 치마를 입으셨어요. (My grandmother wore a skirt.)