The second paragraph of Operational Rule C1same competition.

I suspect that this keeps changing. I'm pretty sure that what wiganermike said used to be the case (a DR player can only play for either the DR club or his registered club). The 2017 rules allowed a DR player to swap and change in the 8's (so long as in a different competition) as long as they'd played at least 8 times for the DR club in the regular season. The 2018 rules reduce that to 5 times or more.

Yep, these rules change every year so it's no wonder clubs get confused, nevermind supporters!
up to 2016: you had to play 8 or more times (I think, but could have been 7- although at least one club ignored this rule and escaped with no more than a slap on the wrist even though they avoided relegation through winning the game the player was involved in) as a DR to be able to play for the DR club in the 8s but you could only play for one or the other club
2017: play 8 times or more and you could play for both if they were in different competitions (8s)
2018: play 5 times or more and you can play for both if they are in different competitions (8s)

It's not easy to find the rules going back but it was, for players with a DR Salary Cap value of over £20k, 3 to play in games for the DR club after the end of season transfer deadline in 2014....although I'm sure they could then only play for 1 or other club.

[iEdit: just found an article confirming 8 games in 2016 (and it would appear continue to play for both clubs which I wasn't aware of until reading it):

Meanwhile Toronto have continued their promotion push, not by playing other clubs players on dual registration, but by signing experienced international Super League players, such as Matty Russell.

Russell said “I’m really looking forward to playing in Toronto. I kept an eye on the club last year and to see how well it was going was great to see for rugby league. For my family to watch me play in Toronto will be an unreal experience!”

Hopefully his wish will come true at some point this season.

They are playing in Toronto this week, likley to be a sell out crowd. Will that be the 1st sell out in the Championship?

Quote: Sir Kevin Sinfield "They are playing in Toronto this week, likley to be a sell out crowd. Will that be the 1st sell out in the Championship?'" It could well be a sell out, given the capacity of Fletchers Fields in Markham, is listed as 3,200! https://en.wikipedia.org/wiki/Fletcher%27s_Fields

Quote: Sir Kevin Sinfield "They are playing in Toronto this week, likley to be a sell out crowd. Will that be the 1st sell out in the Championship?'" It could well be a sell out, given the capacity of Fletchers Fields in Markham, is listed as 3,200! https://en.wikipedia.org/wiki/Fletcher%27s_Fields

Are you sure it's Toronto?

The attendance report from this one will be interesting. Their recent reported attendances were 6 to 7 thousand but have a capacity of 3,200 for this weekend. However, you can still buy tickets for the game (I've just checked). Draw your own conclusions.

It’s about 25 miles from Lamport Stadium.