Design guidelines for RF castellated edge connections
You will generally be using around 50 Ω tracks on the board. It will be difficult to have enough metal around a castellated edge connection to get the impedance down to that, so the connection will look a bit inductive. It will be very short however, so it will be easy to tune up with a sniff of capacitance on either side, to make a low pass filter. This will work until the physical length of the high impedance part starts getting towards a quarter of a wavelength at the highest frequency you want to pass.