Adding SDK to VS project
PCT4 SDK is distributed as a nuget package ProconTel.Sdk. It's available in Macrix public repository: https://nexus.macrix.eu/repository/pct2022/
In order to use please add above link to Package sources in nuget package manager (Visual Studio 2022 example):

Alternatively, you may also execute following command:
dotnet nuget add source https://nexus.macrix.eu/repository/pct2022/ -n Macrix.PCT.2022