RAW settings for D 5100
You need to re-post this question in the forum for the D5100 here http://forums.dpreview.com/forums/1034
I don't have the D5100, but would guess the settings are the same as other models:
In the "Shooting Menu" select 'Image Quality' then select "RAW + JPEG (fine, normal, or basic)"
Then in the "Shooting Menu" select "Image Size" here you will pick the size of the JPEG (raw files are always full resolution) with Large, Medium, or Small. The size will be indicated. I would suggest picking "Small" because you have the "RAW" copy to later make a different size of jpeg from.