This paper investigates the impact of radio frequency (RF) cochannel interference (CCI) on the performance of dual-hop free-space optics (FSO)/RF relay networks. The considered FSO/RF system operates over mixed Málaga-$\mathcal{M}$/composite fading/shadowing generalized-$\cal K$ ($\cal GK$) channels with pointing errors. The {\rm H}-transform theory, wherein integral transforms involve Fox's {\rm H}-functions as kernels, is embodied into a unifying performance analysis framework that encompasses closed-form expressions for the outage probability, the average bit error rate (BER), and the ergodic capacity. By virtue of some {\rm H}-transform asymptotic expansions, the high signal-to-interference-plus-noise ratio (SINR) analysis culminates in easy-to-compute expressions for the outage probability and BER.