Whenever someone applies for a job, it is standard practice to conclude the letter by saying, “I am enclosing herewith my certificates and…”. Some people object to the use of the word “herewith”; they argue that it is redundant. They recommend that people say, “I enclose a copy of….”, or, “Please find enclosed a copy of “.
But the fact remains that even native speakers of English do say, “enclose herewith”. The example provided by the Longman Dictionary of Contemporary English for the word herewith is “I enclose herewith two copies of the contract”.