DIT letter for sponsor applications

[miaki]

Hi Guys
I was offered an employment by a company and they are willing to sponsor me . Currently the company doesn't have sponsorship licence so they need to apply one . The company has less than 20 employees and my job role fall under shortage occupation list . According to Tier2_5 policy guidance the company need to provide a letter of endorsement from UK Trade and Investment (Now known as Department for International Trade ). Can you guys please help me how we can obtain this or any links which has more information. I can't find any information how to obtain this letter anywhere in web

Thanks in advance