Absolutely, and it is extremely important that you do so. In college, we were able to produce a 1 page cheat sheet of common formulas and other related information to use during our exams. These cheat sheets were produced by us, thus, we were familiar with the format and the areas of needed information while taking the test. At times it made it easier, but other times it may have made things more difficult because we either jammed too much information on to the sheet, or did not organize it good enough. The Reference Handbook is no different then these cheat sheets. It is quite a bit larger, and for that reason, it is a must that it is purchased prior to ensure you are familiar from front to back where the certain information is stashed.
Head over to the NCEES website to get the reference handbook or visit the resources page for the direct link.