Hi Vladimir,
Running at 4 MHZ you should not have too many RF issues as the frequency is so low. When you program the chip - make sure the programmer is set to " XT " for 4 mhz if it is set to " HS "or " RC" it will not oscillate with a resonator or crystal. Since 4 MHZ is the default speed for this chip I do not believe you need to DEFINE it in the code, I never have for 4 mhz and they always work. Also make sure no other loads are attached to pins 15 or 16, just the crystal and 22pf caps.
I Hope this helps.
JS