This is a jukugo word, which usually means on'yomi readings from the kanji. This word, however, uses the kun'yomi readings. This is possibly because of 手, because body parts often use kun'yomi. You learned both readings with the individual words, so you should be able to read this.
Ms. Yamashita has a black umbrella in her right hand.
There was a little girl holding a marble in her right hand.
Oh, the baby has a mole on the elbow of his right arm.
The mountain on the right-hand side is Mt. Fuji.