Sounds like you already know how to export your Reefmaster Shaded Relief layer as a Google Earth package then load it into Google Earth Pro to view. To achieve 3D visualization of the Shaded Relief layer in Google Earth, you’ll need to go to the layer’s Properties -> Attributes” tab then select ‘Clamp to Seafloor”. That with drape the image layer on the seafloor. If you have multiple layers stacked, sometime you have to play with the order in which they’re stacked to get it right. Here’s some help article about using altitudes in Google Earth Pro:
support.google.com/earth/answer/148078?hl=en. Good Luck.
These are some examples of some recent Reefmaster projects I've exported to Google Earth Pro to view in 3D
.