For 'job title', you should use 씨 instead of 님. If the person is your customer, then you'd better use '님' instead of 씨.

Thank you both very much for answering my question!! Now I get it!! :)

씨 is came from chaniese character 氏 / 님 is pure Korean character. 씨 is general honorific word to under age(or subordinates) and same age(coworker) 님 is holy honorific word. so we can use 님 to the elder or superiors or customers or stranger whom I want to enhance. 손님 선생님 스님 사장님 선배님 김진표님

I add some more information you would like to know. Sorry about my misunderstanding. It may put you in deep trouble with Korean. Sorry again.