Removal of load-bearing wall in Single-story home

I am looking to hire a professional to provide recommendations on the removal a load-bearing wall in my single-story home. Primarily to determine the size of the supporting beam and determine any other structural conditions that merit consideration. The purpose of this project is to create an open kitchen floor plan and improve the look and functionality of my home. Unfortunately, I do not have the original building plans for my home, and I am unable to obtain them. But we have removed drywall and plaster so as to get a clear view of the current structure. However, I am open to any suggestions regarding the best way to support the load after the wall is removed. If you are qualified and experienced in such projects, it will be a pleasure to work together on this project.
The house is a small craftsman-style home in the highland park district and the span of a possible supporting beam is 16 feet long. The supporting wall now separates the kitchen from the living room. The maximum attic height is about four feet.