Any object that 'floats' on a liquid surface has a static equilibrium between the downward body force (due to downward pull of gravity), a buoyant force due to the displacement of liquid volume by the body, and a surface tension force in the direction of the contact angle (the meniscus angle).
The pin floating in water does not float solely by means of the surface tension, although indeed it is the dominant force. If you look carefully part of the pin is below the surface of the water, and so there is a buoyant force as well as surface tension.
The body forces act on the entire body, although one can resolve all forces at the body's center of mass as a single downward force. Likewise the buoyant forces act on the entire body and can be resolved as a single upward force at the center of buoyancy which is the centroid of the displaced liquid volume.
The surface tension force is a bit different. Think of the surface of the liquid as a net made of small mesh of fibers. An object placed on the net either stretches the fibers around the object or if too heavy, rip the fibers and allow the object to fall through the net. The surface of water for example acts like this net by the stretching of hydrogen bonds which are more plentiful at the surface than within the body of water below. That's because of the air interface above. The surface tension acts along a line, the line that surrounds the body at the water-air interface for example. That's the location where stretching of the bonds takes place and it's why the units are indeed in terms of length not area. It's the force per unit length around this peripheral contact area.
So to complete the vertical equilibrium of the floating object you need to know not only the surface tension force, but also the peripheral boundary (length) and the net contact angle (due to tension and buoyancy). Using this angle to resolve a vertical component. This vertical component can be resolved to a single vector acting upwards at the centroid of the area defined by the peripheral contact line.
If the centers do not line up, there will be moments that cause rotation of the object - until equilibrium is reached.
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