We have provided some guidance as to the level of information your proposal needs to include. In this article, we discuss how to write a business proposal letter and we offer sample letters and templates you can use as a guide.Request for Proposal. The Housing Authority of the County of San Bernardino (HACSB) is seeking a qualified Armed. The proposal must be complete, in the required format, and be in compliance with all the requirements of this RFP. b. Cover Letter (The cover letter to the proposal must be signed and include):. âś“ A one-paragraph description of the project. Forms included within this Request for Proposal must be included with proposal. All vendors must register with OpenGov Procurement (formerly ProcureNow) in order to receive bid solicitations. It is the policy of the San Bernardino County Transportation Authority (SBCTA) to utilize.