I haven't heard of RDF. From other replies in this thread, I'm guessing it's some kind of database schema thing. Or maybe a replacement for JSON / XML. I'm not really sure.

Can you point to a good, comprehensive tutorial that explains the problems RDF is meant to solve, and gives source code of a simple application using best practices?

If the answer is "no," that's the problem right there. If you love RDF, and that tutorial doesn't exist, why don't you write it?