Here is the DAOD reference, the form is not linked:
Report of Injuries and Exposure to Toxic Substances
Your unit will have copies of the form. Ensure you identify witnesses, if any, and ask them to provide statements. (That will save your Pl Comd from tracking them down based solely on the information you provide in the CF 98.) Be as detailed as possible in your statements, these forms are often the sole basis of supporting (or failing to support) claims for medical pensions a decade or two later, when it's impossible to add details.
Don't worry about the DND 663, your unit Safety Officer can fill that one out, thoigh you may be asked for details at some point. The DND 663 is a statistics gathering tool used by the CF to collect data on accidents to look for trends that may help to identify training requirements, equipment deficiencies, etc. They are important in their own right, but whether or not one is completed will not affect your file and the progress of the CF 98.