DXM and Methylphenidate? Man that sounds, well, just awful.
I'm not going to give you a hard time about the questionable recreational value of these two drugs, as I'm sure others won't spare you of their opinions. But honestly, if you are the type of person who likes Dextromethorphan; that spaced out dissociated experience, then go for it. But I think you'd be better off keeping these drugs separate. DXM can put you in some very strange places by itself, and I can only imagine how a stimulant like Ritilan would propel or magnify that weird energy even further.