build.cmd

dotnet build --runtime win-x64 --packages packages

CoreFX.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp30</TargetFramework>
  </PropertyGroup>
  <PropertyGroup>
    <MicrosoftPrivateCoreFxNETCoreAppVersion>4.6.0-preview5.19208.1</MicrosoftPrivateCoreFxNETCoreAppVersion>
    <MicrosoftNETCorePlatformsVersion>3.0.0-preview5.19208.1</MicrosoftNETCorePlatformsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.NETCore.Platforms">
      <Version>$(MicrosoftNETCorePlatformsVersion)</Version>
    </PackageReference>
    <PackageReference Include="Microsoft.Private.CoreFx.NETCoreApp">
      <Version>$(MicrosoftPrivateCoreFxNETCoreAppVersion)</Version>
    </PackageReference>
    <PackageReference Include="System.Text.Encoding.CodePages">
      <Version>$(MicrosoftPrivateCoreFxNETCoreAppVersion)</Version>
    </PackageReference>
    <PackageReference Include="System.Security.Cryptography.Pkcs">
      <Version>$(MicrosoftPrivateCoreFxNETCoreAppVersion)</Version>
    </PackageReference>
  </ItemGroup>
</Project>

NuGet.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageRestore>
    <add key="enabled" value="True" />
  </packageRestore>
  <config>
    <add key="repositoryPath" value="packages" />
  </config>
  <packageSources>
    <clear />
    <add key="dotnet-core" value="https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" />
    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
  </packageSources>
  <disabledPackageSources>
    <clear />
  </disabledPackageSources>
  <activePackageSource>
    <add key="All" value="(Aggregate source)" />
  </activePackageSource>
</configuration>