Ideally, the organic fertilizer that you add to the radish crop should have high amounts of phosphorus and potassium, and sufficient levels of nitrogen. Calcium is an honorary member of the big three when it comes to using organic fertilizers because many of the good ones will contain significant amounts of it as well.
In order to get an idea which fertilizer would work best, you should test your soil beforehand and make your decisions based on the result. However, both blood meal and phosphate rock are good choices when it comes to organic fertilizers because they contain significant levels of nitrogen and phosphorus. Bone meal is not appropriate due to a relatively low potassium content, and should only be used in extreme cases where your soil already has excess potassium.
Another thing that you need to consider is the past of the soil. For example, if the soil has already been heavily fertilized for the crop you planted before radishes, you don't have to use as much the second time.