There really isn't a good way with this particular rule. If it is a finite list of apps trying to inject code into r1win.exe, you could create an app class and add it to the exceptions list that are allowed to do this. Not the best security practice especially if it includes apps like iexplore.exe, winword.exe, etc..
Another method might be to use a Dynamic Application Class. Set it up so that whenever Reflections does "X", all applications are allowed to inject code.
This would be a bit trickier since you have to analyse what causes the process in the first place and have it trigger the exception.