Xiaobaitu, can you help me?

Thank you. My position is Research Associate. It is not tenue-track job, but the funding is easy to be renewed-it is famous funding for chemistry research, and every professor in our university can easy renew it after each two years.
I worry if my offer letter show my selary comes from XXX funding, it easy to make USCIS think it is not a hard-funding because maybe they do not know the character of this funding.
How to show where my salary comes from in this offer letter? or just do not say anything about where my salary comes from?
Thanks for everyone's answer.