I play a Dk and i can not find an addon that will show "killing machine" and "rime."  I tried tell me when, but i have no idea how i add the ablities to it.  also tried scrolling combat text and it doesnt seem to have any DK ablities.  can anyone either tell me how it works or suggest another mod. that will show me a big icon or text in the center of my screen to show when killing machine or rime proc. 

thank you

I personally use Mik's Scrolling Battle Text. I have it set to have sounds play when something like that procs, as well.

http://wow.curse.com/downloads/wow-addons/details/mik-scrolling-battle-text.aspx

MSBT will have a lot of these as part of a default configuration.  If you're missing a specific ability, you can add it in through custom triggers (sig for config on that if you get stuck).

Other possibilities include Parrot, SCT, Power Auras, and TellMeWhen.

 P.S. nice name.

I have found an addon that works perfectly for that purpose: Power Auras Basic

EDIT: Oh, didn't see that it had already been mentioned while I wrote this post... Anyway - I use Power Auras, and it's just great!
For example: on my warlock I have created a warning that pops up whenever Backlash is active; a big glowing flame flashing in the middle of the screen, and for Shadow Trance I've got this cool runed circle glowing purple while zooming in and out, and for Riposte I've got this sweet.... Yeah, I guess you get the point now ;)

The bottom line is: this addon is just simply amazing! You can make custom alerts for everything, and with every possible effect to improve the visibility and coolness - you'll never miss an ability/trinket proc again! :D