Perhaps
=COUNTIF(B3:B17,"*RB*")
However, this will not distinguish between your example "Cris RB TEN" and say "Carbohydrte" or "Curb" or "Herb" etc...
is RB always by itself, with a space before and after?
If so this would work
=COUNTIF(B3:B17,"* RB *")
Notice the spaces.