"Spread it on" is a phrase commonly used to describe the act of distributing a substance or material onto a surface evenly. Synonyms for this phrase include "apply," "smear," "layer," "coat," "paint," and "cover." The choice of the word to use will depend on the context, as each synonym may convey a slightly different meaning. For instance, "apply" is a more general term that can refer to the act of placing something on a surface, while "smear" has a connotation of spreading something in a messy or uncontrolled manner. Using a synonym for "spread it on" can add color and variety to your writing, making it sound less repetitive and more engaging for the reader.