Honestly, I don't think you have to worry about teaching him. There are so many teaching techniques, and you may not have that many in your experience. Kids will learn through games and exposure in the classroom far better than they will sitting at the table with Mom or Dad.
Lots of kids don't go to kindergarten able to read - that's what kindergarten and first grade teach them! What they need is the ability to separate from parents, and the ability to sit in a group and negotiate their own space without whacking the kids next to them. That's pretty much it!
What was the outcome or what were the comments when he went to kindergarten pre-screening? What did the evaluator say? Assuming no one saw a problem, and assuming he has the maturity and social/verbal skills to manage with a bunch of other 5 year olds, I think you should relax and just let things happen.
Even if you are an experienced teacher using a variety of methods with your son, maybe he just doesn't want to focus with a parent. If you do not have experience with different types of learners, maybe your methods just aren't working, or maybe your ability to evaluate "progress" isn't as strong as that of a professional educator.
Kids all come to kindergarten with various skills. Some can read, but those who cannot may do plenty of other things ahead of the reading kids. It all balances out!
I think the worst thing parents can do is to push kids in a certain structured learning environment (perhaps the way you learned was good for you, but not for him) or sit them down with workbooks. It makes learning stressful for kids, and they will resist. Kids in school learn when they don't even realize it. Don't let other parents get you into a competitive mindset for just one subject (reading) at the expense of the many things kids need to learn!
Read with him, every day. For fun. For closeness. For stimulating stories, For adventures. For a topic that interests him. Don't make him study letters with you! Make learning a byproduct of your reading joys, not the focus of the day.
Keep telling yourself: He's 5. Five. He has 13 years of school ahead of him. He will work it out.