public GraphicsBuffer vertexBuffer { readonly get; set; }

Define the vertex buffer format by specifiying a list of vertex attributes in RayTracingMultiGeometryInstanceConfig.vertexAttributes array.

You can use a common vertex buffer as a pool to define multiple geometries used by ray tracing instances that have different properties (for example different materials).

Specify for the GraphicsBuffer.Target parameter when creating the vertex buffer from scripts. If the buffer is also used in rasterization then add the flag.