There is no such RF Layout Fundamentals..There are some Basic Principles and Rule of Thumbs while designing a RF PCB or MMIC/RFIC Layout.
Furthermore, PCB and MMIC/RFIC Design Rules are quite different and each designer has some habits and rules.Basic Fundamental for generic RF Layout, it can be said :
-keep your traces about lambda/10 long in your circuit for phase stability.
-make sure to do em simulation to observe how your current travels through the PCB.
-use proper DC-block and RF-choke elements for DC/AC balance of the circuit
-model your circuit schematic as close to real-case including transmission lines, parasitics etc.