  In this work, we present follow-up observations of two known repeating fast
radio bursts (FRBs) and seven non-repeating FRBs with complex morphology
discovered with CHIME/FRB. These observations were conducted with the Arecibo
Observatory 327 MHz receiver. We detected no additional bursts from these
sources, nor did CHIME/FRB detect any additional bursts from these sources
during our follow-up program. Based on these non-detections, we provide
constraints on the repetition rate, for all nine sources. We calculate
repetition rates above 1 Jy using both a Poisson distribution of repetition and
the Weibull distribution of repetition presented by Oppermann et al. (2018).
For both distributions, we find repetition upper limits of the order $\lambda =
10^{-2} - 10^{-1} \text{hr}^{-1}$ for all sources. These rates are much lower
than those recently published for notable repeating FRBs like FRB 20121102A and
FRB 20201124A, suggesting the possibility of a low-repetition sub-population.
