I will be honest only ever used the ISO files.
Installation is the same as any other virtual machine.
ie create the vm, attach the ISO
Boot the vm off the ISO and will install
Will ask you to configue an Interface with an IP during the installation.
You should be able to connect to that IP with the WebUI that allows you to complete the initial config wizard.
Haven't used the OVF files personally since R77.10 however installation will be for a pre-prepped Hardware with
Only guide I could find was for an R77 installation however I figure will be pretty similar and should be able to adapt.
https://dl3.checkpoint.com/paid/2d/2d125be1fdc516aeec2f819e3e56d55c/CP_R77_SecurityGatewayVE_NM_Admi...
Your ESXi admin should be familar with how to manipulate within ESXi.
The Cloudguard Docs https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solut... don't cover Onpremise ESXi that could find.
Don't know if anyone else here done more with OVF installation that has more detailed information about the OVF and if they differ from the ISO installation on vmware in ESXi