According to the user manual provided, the water filter location for the Samsung RF29DB9900QD refrigerator is inside the refrigerator compartment.
Specifically, according to pages 82 and 83 of the English version of the manual, the water filter is a cartridge inserted horizontally at the fridge section, behind a cover.
The manual shows illustrations of the cover and the cartridge, along with steps on how to replace it (shutting off water, opening the cover, turning the knob, pulling out the cartridge, etc.).