Hi Alex; The Si app note is showing it as meant to be connected to a higher impedance than your headphones (which are defined as 32 ohms standard now). In order to get the same 10 Hz -3 dB point, the impedance of the (inferred) input it drives must be over 40 k ohms; you need to drive 32 ohms, and therefor, the capacitor required is 470 uF. There must be a volume control, or users can be harmed by it being too loud. The output of that chip is not likely designed to drive 32 ohm loads, and that should be evident by the 0,39 uF output capacitors which indicate a load of > 40 k being driven.
I'll help you get a headphone amp on this board if you wish, or show you how to produce a line level output for driving an outboard powered speaker or headphone amp. Include just the schematic of a proper headphone amp if the board size will not allow it.
Never ever use a ceramic capacitor to couple audio by the way, they introduce distortion and just plain sound really bad. Use films for up to 1 uF or so and bipolar elecrolydics specifically designed for audio coupling for higher values. Use Nichicon ES Audio rated bipolars and you cant go wrong- http://www.mouser.com/ds/2/293/e-es-3258.pdf
I strongly recommend a volume control into a proper headphone amplifier such as an SSM 2135 (best choice for you).
The zero ohm is just a jumper to allow flexibility. If you just put the pins as I suggested, no jumper is needed. No app note with a short antenna will apply unless you can *tune* the values with RF gear. If the user just puts a one meter wire to the input at the pins, the FM performance will be better than any small ant on the board- they are useless for this frequency; that's why there are not FM radios inside cell phones. FM needs a longer antenna than can be put on a little PCB
AM is another story, with an air core tuned loop being the best option, so leave that totally open with just a connection and allow people to make proper antenna or 75 ohm cable input interfaces to it.