This shader is considered deprecated and will be removed in a future release. You should use the Standard Surface shader instead.
A tutorial that covers how to use the Skin shader can be found here.
In order to render Skin (SSS) across multiple objects you must use SSS Set Name.
The Skin shader can also be used to create a wide variety of materials such as wax, clay, marble, milk and plastics. Below are some more examples of different materials that can also be achieved with the Skin shader using different presets.
Further Skin shader examples