There is no information about installing the D-Link DES-1016C on the rack. I see some holes on the side of the chassis (as shown in the picture), however, there is no info about expansion brackets for that.
I googled the product and found this accompanying picture from a Russian site. Looks like there may be bracket adapters - but not sure. <https://nvartovsk.nix.ru/autocatalog/networking_d_link/D-Link-DES-1016C-A1A-Neupravlyaemyj-kommutator-16UTP-100Mbps_266570.html#pid=2296>
You could query DLink support for specifics.