Hello Sameer,
We do not support QuickBooks online, only the desktop version.
There are some 3rd parties that do the conversion with some success but I cannot recommend it as a real solution.
If the IIF file exporting works, it's 10 seconds to add rate, as we already have it in the timesheet record from the Clarizen side.
The rate is not there by default as the QB desktop version do not supports import of rates (which the online version do). As a workaround in the desktop version we are importing rates into the service item.
Billing information can also be extracted, but it required a bit more effort/customizations.