It sure is! Very simple actually. All you need to do is add the target="_blank" attribute to your link within the new meta field. Directions below :)
First thing is you need to add the new meta field to your portfolio post. You can do that in the Angular options under portfolio. Just click on the little + symbol underneath one of the pre-existing ones. Name that Site URL or whatever title you want to give it.
Now go to your portfolio item. On the lower right you'll see the new Site URL meta field. Any link you place in here needs to be in the following form:
<a href="http://google.com" target="_blank">Google</a>
I just used Google as an example, you would need to replace the url and title with your own.