Hi all
looks like viki’s help pages with respect to their Roku app/channel are out of date, because as of the time of posting, I can install the Viki app on my Roku and I am in the United Kingdom which is apparently not one of the supported countries, according to viki’s help pages.
Other United Kingdom users that have Roku’s may wish to attempt to install it 
let’s just hope they are just being slow at updating out pages and website, and it’s not a mistake, because if it is, it will probably be removed again Shortly.
Certain Roku models have been officially available in the United Kingdom for a long time, (be careful what model you buy. If you’re in the United Kingdom) but Roku hasn’t been supported by viki for UK users. Hopefully this has now changed.