timer_reset wasn't fully implemented for all timers on all series, and was simply a wrapper of the RST bits in the RCC registers anyway. First part of https://github.com/libopencm3/libopencm3/issues/709
Examples in these directories are not only for the board listed, they are simply preconfigured for those boards. If you do not find an example of the peripheral you want to use listed for your board, please look at the other boards. The differences between boards for the examples is normally only LEDs and buttons on different pins, and different memory sizes.