Tested on macOS 10.13 with VirtualBox 5.2

Create OpenBSD VM in VirtualBox

Download ISO image of the OpenBSD installer.

Start VirtualBox.

macOS VirtualBox

Select from the menu Machine > New…

In Name and operating system:

Name: foo
Type: BSD
Version: OpenBSD (64-bit)

Click Continue.

Name and operating system

In Memory size select at least 2048 MB.

Memory size

In Hard disk select Create a virtual hard disk now.

Hard disk

In Hard disk file type select VDI.

Hard disk file type

In Storage on physical hard disk select Dynamically allocated.

Storage on physical hard disk

In File location and size keep default file location (~/VirtualBox VMs/foo/foo.vdi) and size (16 GB). OpenBSD fits into 1GB, but you’ll need some space for your programs and data.

Click Create.

File locaton and size

Select from the menu Machine > Settings…

Select Storage, then select Storage Devices >Controller: IDE > Empty.

In corresponding Attributes click on CD icon near Optical Drive: IDE Secondary Master and select Choose Virtual Optical Disk File….

Pick the previously downloaded OpenBSD installer ISO image.

Click OK.

Select from the menu Machine > Start > Normal Start. OpenBSD installer boots in a new window…

Install OpenBSD