I guesstimate a pound of propane per 24 hours.
My five notes about absorption fridges:
1: Level them. I use at less than 3 degrees from level as my guide. Otherwise the fridge will destroy itself over time.
2: Use a screen on the vents. Mud daubers and hornets love fridges to make their home in. Similar with spiders... they just love the smell of propane.
3: Use fridge fans. One can install some, but I use the cheapie Valterra fans that use two "D" batteries and last for 4-6 weeks. It isn't much air, but it makes a big difference in cooling. Similar in the flue. A "computer" fan in the right place can help a lot.
4: Check for recalls, and if one is needed, get it done, or chuck the fridge and buy a new one.
5: Since the freezer gets cold within a few hours, I like using hard-sided freezer packs. I keep a couple in the freezer, rotate them into the fridge every so often (around daily.) This keeps the fridge part cool, especially with a small fan mentioned in #3. As an added bonus when on the road for fairly short distances (2-4 hours), the freezer packs keep the fridge at a safe temperature without needing to use propane while on the road.