How to be sure that a ceramic capacitor can manage a RMS current?
The allowed RMS current appears to be rarely mentioned in ceramic capacitor datasheets. Have a look around for additional information provided by the manufacturer on their website. KEMET for example provides a lot of information in their design tool KSIM. They also provide the most important data in additional specsheets, e.g. C0805C106K8RACTU.
You can directly reference the max RMS current characteristic:

Other manufacturers like TDK don't directly provide the current curve, but the ESR and Ripple Temperature Rise curves. They also state in their specification, that the temperature rise at the capacitor surface should be below 20°C. Example plots:


Source:TDK C2012X7R1A106K125AC Characterization Sheet
So using the ESR graph and the Temperature Rise graph at the same frequency, you can easily calculate the maximum power dissipation:
$$P_{max} = ESR \times I_{RMS}(20°C)^2$$
And with the ESR at your frequency of operation you can then calculate the maximum RMS current.
Popular manufacturers like Murata, Samsung, AVX etc. all provide this kind of information. But the datasheet that is provided on the websites of the distributors is often more like a catalog than actual data. Make sure you check the manufacturers website for this kind of information for the specific capacitor of interest.