Is perfect-forward secrecy achieved with RSA? I am new to cryptography and am going through the book Understanding Cryptography by Paar and Pelzl. 

From what I understand Symmetric key distribution systems like Kerberos do not provide PFS because an attacker will be able to decrypt every session key ever encrypted with a compromised KEK.

In the book, on page 342, they say that Asymmetric ciphers like Diffie-Hellman or RSA, when used for key distribution, will provide FPS. I understand that Diffie-Hellman will provide PFS because each session key will have nothing to do with any other session key. However I've been stumped for a few days now trying to figure out how RSA will provide PFS. Am I missing something or just misunderstanding what they wrote?
This expands CodesInChaos's comment into an answer.

Forward Secrecy (that is, maintaining confidentiality of messages enciphered before compromise of the long term key) can be achieved in a protocol using a public-key signature scheme with a long-term public key, and a public-key encryption scheme with a per-session key; but in the case of RSA signature and encryption, that's inefficient, thus unusual.

As an example: Bob has a long-term RSA key pair $(Mpub_B,Mpriv_B)$ used for signature, with $Mpub_B$ trusted by Alice (perhaps by way of some certificate). In order for Alice to send a confidential message to Bob:


Alice


draws a 256-bit random $R$
sends $R$ to Bob

Bob


generates a new RSA key pair $(Tpub_B,Tpriv_B)$ used for encryption,
RSA-signs the (hash of the) message $R\|Tpub_B$ using $Mpriv_B$ giving signature $S$
sends $Tpub_B\|S$ to Alice

Alice


gets $Tpub_B$ and $S$
verifies that $S$ is a valid signature with respect to $Mpriv_B$ for $R\|Tpub_B$, where $R$ is from the recent first step
generates a random symmetric session key $K$
RSA-enciphers $K$ using $Tpub_B$ yielding $X$
enciphers the plaintext message $M$ using key $K$ by a symmetric algorithm (say, AES-CTR will implicit zero IV) yielding ciphertext $C$
forgets $K$
sends $X\|C$ to Bob

Bob


gets $X$ and $C$
RSA-deciphers $X$ using $Tpriv_B$ yielding $K$
forgets $Tpriv_B$
deciphers ciphertext $C$ with key $K$ yielding plaintext message $M$
forgets $K$.



$K$ allows $M$ to be large, when RSA encryption only directly allows short messages. $R$ protects against replay of an earlier $Tpub_B$.

The scheme is inefficient because the generation of a new RSA key pair is relatively expensive (and normally rare, thus not optimized for speed). That's a good reason why (EC)DH is most used in practice.

It is possible to send several messages using the same $K$, or/and reuse $(Tpub_B,Tpriv_B)$ across multiple sessions, improving performance. But Forward Secrecy triggers only when $K$ and $Tpriv_B$ are forgotten, and $R$ is no longer accepted.

Note: the scheme provides confidentiality, but not integrity or proof of origin; that can be added.