The really easy part is it can happily run Docker containers:

    $ sudo bin/rkt --insecure-skip-verify run --interactive docker://busybox
    rkt: fetching image from docker://busybox
    Downloading cf2616975b4a: [====================================] 32 B/32 B
    Downloading 6ce2e90b0bc7: [====================================] 1.15 MB/1.15 MB
    Downloading 8c2e06607696: [====================================] 32 B/32 B
    2015/08/28 12:15:24 Preparing stage1
    2015/08/28 12:15:25 Writing image manifest
    2015/08/28 12:15:25 Loading image sha512-9d710100ce6769569b12a39100318bfed5b6b98115ee6315b724c11658db3751
    2015/08/28 12:15:25 Writing pod manifest
    2015/08/28 12:15:25 Setting up stage1
    2015/08/28 12:15:25 Wrote filesystem to /var/lib/rkt/pods/run/e3cbf309-5f03-4ce4-b098-597b5ec3e040
    2015/08/28 12:15:25 Pivoting to filesystem /var/lib/rkt/pods/run/e3cbf309-5f03-4ce4-b098-597b5ec3e040
    2015/08/28 12:15:25 Execing /init
    / # ls -l $(which ls)
    lrwxrwxrwx    1 root     root             7 May 22  2014 /bin/ls -> busybox
    / # exit
    Sending SIGTERM to remaining processes...
    Sending SIGKILL to remaining processes...
    Halting system.

The `--insecure-skip-verify` is to disable the GPG verification that rkt does for its native ACI container format. Beyond that, take a look at `rkt help run` and poke around.