In case you want to run an AB test for an RSA ad, you need to first create a copy of the RSA and then make necessary modifications (e.g., test a fully pinned RSA vs its unpinned copy, or have different messages pinned at headline 1 in both versions of the ad to see which one performs better). Adalysis provides you with all the tools you need to create RSAs in bulk and quickly make the necessary adjustments.
You can check this video where the A/B Testing workflow for Responsive Search Ads is described in more detail.
Step 1. Find and select the RSAs you want to copy
From within the Ads screen, use the necessary filters (such as campaign, ad groups, text in the ads, labels, etc.) to find the RSAs you want to copy.
Step 2. Copy selected ads
Use the Tools > Copy RSAs menu option to open the tool. 
The label field is mandatory as this is how you will be able to find your newly created RSA afterward to make the necessary copy and pinning changes. Either select one of your existing labels or create a new label by going to Ads → Labels → Manage labels → Create new labels.
In addition to copying the RSA ad copy, you can also copy the pinning of the original RSAs in the new ads by checking the checkbox Keep the same pinning as in the source ads.
The new ads will be created in the ad groups where the original ads are.
Step 3. Modify newly created RSAs
You can now use the RSA Asset Manager to change the assets of the newly created RSAs to any other variation.
This will open the Asset Manager where you can make bulk changes to a set of RSAs. Use the filters at the top to quickly find the newly created RSAs by the ad label you used in the previous step.
You can now make the necessary changes in the copy or change the asset pinning in the newly created ads.