JRemote on iOS will display PDF booklets that are in the folder of whatever is currently playing. However, you must configure the library import task to include PDFs, which JRiver classifies as "Data", and the "Data" option disappears when Audio Only mode is checked. So the answer is no, unless you aren't interested in seeing related files on an iOS device. JRemote on Android doesn't support this feature yet, but I hope that someday it will.
