I love Robinson-Anton rayon, but I also use Brother, Isacord and Sulky as well ad Madeira Rayon..... My Pfaff liked the Madeira the best, but my Brother really loves the Robinson-Anton. I go with what price is the best and the color I need depending on the store I am shopping in and remember I need some.
I also really like the polyneon finish.
For a search of sites, just Bing or Google the name and many sites pop up.
Good luck on your search.