Use the 5th coin (reindeer) on the left machine.
For more detailed strategies, you can find community-made guides on TrueAchievements or GameFAQs . Syberia 2 Achievements | TrueAchievements Syberia 2 XLBA - Xbox 360 [Arcade]
In the Cliff puzzle, click above Kate's head to climb and to her shoulder height to move sideways. Use the 5th coin (reindeer) on the left machine