If you are using the Visual Studio Toolbox (described further below) to add instances of components to your project, the assembly references are created for you by Visual Studio automatically, when you drag the component onto the designer’s surface.

This is the approach used in the "Getting Started" articles:

• Making a first OPC Classic application using Live Binding in Windows Forms
• Making a first OPC Classic application using traditional coding
• Making a first OPC UA application using Live Binding in Windows Forms
• Making a first OPC UA application using Live Binding in WPF
• Making a first OPC UA application using traditional coding

This technique only works for certain kinds of projects (such as Windows Forms or WPF) and certain kinds of project items in them.