I sure wish I could help you out. I don't have any redfoots, just sulcatas and a Russian. Redfoots are gorgeous though. Give it some time and you'll get responses.
I only have two Cherry Head's so.... My oldest was 3 years in July, and he was 7 in. in Sept.
My hatchling was born in June 2010 and was 1.8 in, and as of yesterday he is 3 1/4 in.
My hatchling was born April 24th and is at 3 1/4" right now.
Growth rates will vary a bit with the individual tortoise, but I've heard they get half their adult size in 5 years and then half of however that big was in the next 5 years. After that growth slows down a bit. Not sure how accurate that is yet though so take it with a grain of salt.
There are a lot of variables, including space, care, nutrition, and genetics. There is no set rate as to how fast they grow.
My baby was born the beginning of July, and is 3 1/4" as well. So as you see, three babies, born in April, June, and July, are all the same size. Mine started out smaller than normal as well, but quickly caught up.
The majority of growth occurs in the first few years, and growth slows towards adulthood and beyond.
How big is your Redfoot now, and how big is your enclosure?
I have found over the last 5 years ...once into " junior" stage 4" they tend to grow about 1/2" SCL per year untill reaching adult hood and finally " sizing out" ..