Dear Andrew,
If you want to look into more detail the issue of peanut allergy, you may have a look at this recent report of the US National Institute of Allergy and Infectious Diseases.
Togias A, Cooper SF, Acebal ML, Assa'ad A, Baker JR Jr, Beck LA, Block J, Byrd-Bredbenner C, Chan ES, Eichenfield LF, Fleischer DM, Fuchs GJ 3rd, Furuta GT, Greenhawt MJ, Gupta RS, Habich M, Jones SM, Keaton K, Muraro A, Plaut M, Rosenwasser LJ, Rotrosen D, Sampson HA, Schneider LC, Sicherer SH, Sidbury R, Spergel J, Stukus DR, Venter C, Boyce JA. Addendum Guidelines for the Prevention of Peanut Allergy in the United States: Summary of the National Institute of Allergy and Infectious Diseases-Sponsored Expert Panel. J Acad Nutr Diet. 2017 May;117(5):788-793. doi: 10.1016/j.jand.2017.03.004.
https://www.ncbi.nlm.nih.gov/pubmed/28449793
In case of mild to moderate eczema, they advise to give peanuts containing foods at around 6 months of age. See table. In case of severe eczema, they advise to measure peanut-IgE or do a skin test and if found negative to give peanuts containing foods. So no real rationale for not giving RUTF in SAM children with mild eczema. And if you want to do a study to ivestigate the problem, consider measuring peanut-IgE or skin tests and avoid ascribing any skin problem to peanut allergy.