или надо руками наколотить?

https://www.safaribooksonline.com/library/view/rtf-pocket-guide/9781449302047/ch04.html

ASCII-RTF Character Chart
Table 4-1 shows the main printable characters you can access in RTF, as defined by the ANSI character set (also known as Code Page 1252, which is basically Latin-1 with some characters added between 128 and 159). Accessing Unicode characters is explained in the Character Formatting section of Chapter 1.

Note that while RTF escapes (\'xx) are valid for all characters, the only characters that have to be escaped are these three characters: {, }, and \, plus all the characters over code 127.

Нашел такое, но там есть дырки

You can materialize a table with the ASCII codes or create one dynamically in a query. But be aware that only the code points 0-127 are ASCII characters. Characters in the range 128-255 are determined by the character code page (collation in SQL Server):