Help excluding all of an expression except for two specific expressions


I've been using knime to play around with my company's SQL database and I'm looking to ommit everything except a certain expression but can't for the life of me figure out how to go about this. The format of the colum in question is "WXRE3257903_R1" etc. or it could be "RTSO283746_F1". so what i'm looking to do is to assign a boolean value to "_R1" and "_F1". to do this, i need to find a way to filter out all of the rest of the data, which can be of different lengths and formats. the only common factor is the _F and the _R.


Any help would be greatly appreciated,


In terms of a regex expression, how about something like