You can create your own collision detection with SFML.
All you need to detect collisions in any situation is the position and size of the objects.
With SFML's graphic package, all sprites already have a position and a rectangular shape.
To imagine this, here is a little ascii art of a rectangle with the calculations to get all four points of the rectangle:
(x, y)-----------------------(x + width, y)
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(x, y + height)-----(x + width, y + height)
Using the greater than and less than operators, you can easily see if one sprite's rectangle is overlapping another's.
This should suffice for a simple 2D RPG.
Study into collision detection a bit more though and using the same concepts you can create pixel perfect collision detection in SFML.