How to find functional dependancies from simply looking at a relational schema?
You can't tell the functional dependencies just from the schema.  

If you knew that the schema was in third normal form (3NF) or higher and you knew that there are no other candidate keys other than the primary key, then you would know that every non-key attribute was fully functionally dependent on the primary key.

Except for this particular situation, there is nothing about a schema that conveys functional dependency.  The purpose of a schema is to convey table structure, not functional dependencies.