When I do a RCM, I record everything on a graphical data sheet I got from Sierra Building Science. It has all of the pressure and temperature data entries labeled on a system diagram. On the backside of the sheet is the duct test stuff, equipment info, and client info.
The best part is that the forms are laminated and I use a Sharpie marker pen to write down the data. If you ever had to write info down on paper when it suddenly starts to rain, the paper turns into mush very quickly. The plastic laminate form and sharpie allows me to keep on working. When I get home, I xerox the laminated form for a permament copy and reuse the laminated form again. To remove the Sharpie markings, a little alchol and paper towel is needed.