ex: from that https://github.com/maartenhofstede/xamarin.plugins.beaconmanager
I am assuming you have compiled the project so a .nupkg file is available. To be able to install this into a project you can add a new package source that points to the directory that your .nupkg file is stored.
With VS on Windows you can create a package source pointing to a directory using the browse button as shown in this screenshot.
VS for Mac and Xamarin Studio have a similar way to create a local directory package source in preferences - NuGet - Sources when you click the Add button.
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