Just those elements, each once? No, that's not likely to be a compound that exists. Now, a large, carbon-based molecule, that can trap one Re and one La atom? That might be doable. If you can design such a molecule (look up the chemistry of organic compounds of Lanthanide elements,) draw it out as a skeleton (so don't display hydrogen atoms in the structure,) and then do something stylized with the structure (because who wants an actual molecule on their body -- tattoos are often abstract, unless mermaids actually exist, and I've just missed seeing them,) then you might have something interesting.