Questions about ATA8510 antenna and passive component values

I really hope this in the right place! I'm in the process of working on a project that will hopefully use Atmel's ATA8510 in standalone configuration at 868.3MHz. I've run into something of a roadblock. There aren't any additional application documents that reveal what the value of each component should be (seen on pg 10) and I don't know enough about filters and this uC to do this without what seems like necessary information (I intended on putting a harmonic filter as per an earlier note in the pdf on pg 9). I'm also wondering If I could use a quarter whip antenna instead of a loop antenna. If someone could help me out with choosing component values and/or point me to some quality literature for RF theory or some prerequisite material it would be greatly appreciated.
The datasheet is here

EDIT: I re-read my post and it seems kinda vague. This version is more succinct.

I'm going to preface this by saying that my RF and filter knowledge is extremely limited.
The first thing I'd like to address is the antenna. I cannot find any details about an antenna that would be sufficient for this chip at 868MHz. I was thinking of using a flex pcb to create a loop which terminates in regular pads but I am unsure of the optimal dimensions/shape for the antenna.
The second problem I am encountering is that I cannot seem to find the values for inductors and capacitors inn the reference application schematic (page 10 of the data sheet).
My last issue is with the harmonic filter I would like to add to the SPDT_ANT input. I don't think I can create such a filter with an equivalence of 50ohm without knowing the load resistance, which i'm assuming changes when switching from rx to tx. please advise on this matter. I would greatly appreciate any help.
Thanks,
Avi