I purchased my foil and circular studs from www.dollarnailart.com
To transfer the foil you need special nail foil transfer glue. I got the foil and glue at the same site and that's also the site where I get all my square and round studs from. The only con is that you have to spend a minimum of $25.
This is what the foil and glue look like:
The foil comes in those little tubes and you just cut some to fit your nail. I still haven't tried to put the foil on my entire nail because I love the way it looks with the base color showing.
If you want to achieve this look here's a YouTube tutorial:
Have a beautiful day!