RB5009 does not fit in the 10" rack using the K-79 kit.
However, there are some customer reports that it can fit in the 10" rack using the short ears of the K-79 kit, but it is a snug fit. Per the 10" rack specification its inside width is 222.25mm, but the RB5009 including rack ears is 225mm wide ( its 2.75mm wider). The only option is to make some small modifications to the rack to create wider space for the device.