Can someone give me some advice or point me in the right direction on where to start?
Can I go down to the supermarket and buy bulk frozen chicken? How much do I feed her in a day?

She's 8 months old and weighs 58 pounds.

Thanks!

These were especially helpful for me in the beginning:

http://www.rawdogranch.com/

http://pets.groups.yahoo.com/group/rawfeeding/ (this group especially**)

http://naturalrearing.com/coda/l_common_sense.html

There are a few different kinds of raw diets, I feed PMR which does not include veggies. In the beginning I kicked up the amount of bone to help with stool formation as it's a big change for them. I did not "gradually" introduce raw. They had kibble one night and raw the next.

You'll aim for 2-3% of her expected weight but with puppies who are still growing I usually start at 3% of their current weight and go from there. If they're gaining too much i'll kick it back and if they're looking too thin i'll kick it up. These measurements are per day. Everything is trial and error with raw, each dog is different.

We are slowly working our way towards trying out the PMR diet with Brewer, and I have found this thread to be very informational:

https://www.itsahuskything.com/t1256-considering-a-raw-diet

I do I guess a mix of the different raws. I mostly give them the PMR version, but once a week they get brown rice and raw veggies as well. We started with chicken, bulk frozen chicken, and now have introducted pork to them (mainly neck for our little ones and ham hocks for the big ones).

Like Kristina said, it's all trial and error. Kya wont eat drumstick, and our great pyr mix wont eat wings, so we just buy the bulk and cut it up, giving each dog what they like

58 lbs is not bad for a female GSD maybe a few pounds on the heavy side but nothing bad. Are you trying to make her gain weight or lose weight? Her weight is slowing down she will probably top out at 65-70 lbs when she done growing.
I have a 2 and a half year old GSD male. He is at 100 lbs but his dad was a size of a horse...lol

I would like to her maintain a healthy growth rate, not trying to lose any. I want to switch to raw because I've heard such great things about it and I'd like to know where to begin, what to feed all that stuff.

Thanks for the information guys!