@ Jim; thanks for verifying that mate, much obliged.
Just as a "caution" for anyone using this routine, the setting TC_SetRA doesn't appear to be doing what the routine claims it does; We've varied its value and the pulse ratio seems "stuck" (or remains) at around 50%. We're investigating at present and will post updated code that - hopefully - takes a PWM percentage as well as a Frequency as part of its calling parameters. Much easier for us that way, and for anyone who wants to use it that way.