knit(\'test2.rnw\')
processing file: test2.rnw
|>>>>>>>>>>>>> | 20%
Just FYI, now knitr will automatically add /tex/texbin to PATH for Mac OS if it is not already in PATH.
Installing texlive-latex-extra solved for me. The original answer (https://stackoverflow.com/a/25517332/1169233) is intended for Ubuntu, but AFAIK it should work verbatim on Mac OS too.