There are two versions of the rf generator. The more complex version was described in "A Simple Radio-Frequency Power Source for Ion Guides and Traps", Ronald M. Jones, Dieter Gerlich, and Scott L. Anderson, Rev. Sci. Instrum. 68 (1997) 3357-62. You can download the original article here and you can find more detailed construction information here.
This more complex version includes ability to add DC offsets (useful in calibrating the rf effective potential), and also a high speed keying circuit that can ramp the rf up and down. This keying circuit adds substantially to the complexity, and 99% of applications don't need it.
We also published the design for a much simpler version of the the rf generator: "Simplified Radio-Frequency Generator for Driving Ion Guides, Traps and other Capacitive Loads", Ronald M. Jones and Scott L. Anderson, Rev. Sci. Instrum. 71 (2000) 4335-7, which can be downloaded here. This version does not have the capability for DC offsets (though you can easily add that part of the circuit from the more complex design, and also uses fixed capacitors instead of the expensive air-variable capacitors. You give up the ability to fine tune the rf frequency, but for most applications, who cares?
For both the complex and simplified versions of the rf generator, we have found it useful to make a change in the design of the tank circuit, as shown below for the simplified version. The imporant change is that the single capacitor (Ctune) used to set the frequency of the tank circuit has been replaced by a pair in series, with the center tap grounded. This design improves stability of the oscillator, and allows it to operate over a much wider frequency range. In my lab, we currently have versions running at frequencies from a few hundred kHz to 10 MHz.